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  • 1.
    Abdu, Yassir
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Annersten, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Coexisting antiferromagnetism and ferromagnetism in mechanically alloyed Fe-rich Fe-Ni alloys: Implications regarding the Fe-Ni phase diagram below 400 °C2004In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 280, no 2-3, p. 395-403Article in journal (Refereed)
    Abstract [en]

    Fe–Ni alloys below the Invar region with compositions Fe100−xNix (x=21, 24, and 27 at%) were prepared by high-energy ball milling technique (mechanical alloying). The as-milled samples, characterized by X-ray diffraction and Mössbauer spectroscopy, contain a mixture of α (BCC) and γ (FCC) phases, whereas the samples annealed at 650°C for 0.5 h show a single γ (FCC) phase displaying a single line Mössbauer spectrum at room temperature (RT). At low temperature, the Mössbauer spectra of annealed Fe76Ni24 and Fe73Ni27 alloys show the existence of a magnetically split pattern together with a broad singlet, which are ascribed to a high-moment ferromagnetic Ni-rich phase and a low-moment Fe-rich phase, respectively. The Fe-rich phase in annealed Fe76Ni24 alloy, which is paramagnetic at RT, undergoes antiferromagnetic ordering at ∼40 K, estimated from the dramatic line broadening of its spectrum, giving rise to a small hyperfine field (e.g. ∼2 T at 6 K). The coexistence of these phases is attributed to phase segregation occurring in these alloys as a result of enhanced atomic diffusion. The stability of these alloys towards martensitic (FCC→BCC) transformation at low temperatures is discussed in connection with the Fe–Ni phase diagram below 400°C.

  • 2.
    Abdu, Yassir
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Physics, Department of Physics and Materials Science, Physics III. Technology, Department of Engineering Sciences, Solid State Physics.
    Ericsson, Tore
    Department of Physics. Physics, Department of Physics and Materials Science, Physics III. Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Physics, Department of Physics and Materials Science, Physics III. Technology, Department of Engineering Sciences, Solid State Physics. Fasta tillståndets fysik.
    Field-induced local magnetic moments in γ (FCC) Fe-Ni anti –Invar alloys2004In: J. Mag. Mag. Mater, Vol. 280, p. 243-250Article in journal (Refereed)
  • 3. Aksenov, V. L,
    et al.
    Jernekov, K. N.
    Khaidukov, Yu. N.
    Nikitenko, Yu. V.
    Petrenko, A. V.
    Proglyado, V. V.
    Andersson, Gabriella
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Wäppling, Roger
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Interplay between superconductivity and ferromagnetism in Fe/V multilayered structure studied by polarized neutron reflectometry2005In: Physica B, Vol. 356, p. 9-Article in journal (Refereed)
  • 4.
    Andersson, Gabriella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Burkert, Till
    Warnicke, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Björck, Matts
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Chacon, Cyril
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Zlotea, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Nordström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys2006In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 96, no 3, article id 037205Article in journal (Refereed)
    Abstract [en]

    We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe(0.36)Co(0.64)/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210 mu eV/atom, and a saturation magnetization of 2.5 mu(B)/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values 150 mu eV/atom and 2.2 mu(B)/atom are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials.

  • 5.
    Andersson, Gabriella
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Zabel, Hartmut
    Hydrogen-induced lattice expansion of vanadium in a Fe/V (001) single-crystal superlattice1997In: Physical Review B, Vol. 55, no 23, p. 15905-Article in journal (Refereed)
  • 6. Andersson, L.-O.
    et al.
    Bäcklund, A.
    Bergmark, T.
    Byström, O.
    Calen, H.
    Einarsson, L.
    Ekström, C.
    Fransson, J.
    Gajewski, K.
    Haag, N.
    Hartman, T.
    Hellbeck, E.
    Johansen, T.
    Jonsson, O.
    Lundström, B.
    Peterson, R.
    Pettersson, L.
    Prokofiev, A.
    Reistad, D.
    Renberg, P.-U
    van Rooyen, D.
    Wedberg, R.
    Wessman, D.
    Westerberg, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Ziemann, V.
    A NEW MONO-ENERGETIC NEUTRON BEAM FACILITY IN THE 20-180 MeV RANGE2004In: A NEW MONO-ENERGETIC NEUTRON BEAM FACILITY IN THE 20-180 MeV RANGE, 2004Conference paper (Other scientific)
  • 7. Andreeva, M. A.
    et al.
    Lindgren, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Nuclear resonant spectroscopy at Bragg reflections from periodic multilayers: Basic effects and applications2005In: Phys. Rev. B, Vol. 72, p. 125433-Article in journal (Refereed)
  • 8. Andreeva, M. A.
    et al.
    Smekhova, A. G.
    Lindgren, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Björck, Matts
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Andersson, Gabriella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Depth selective investigations of magnetic multilayers by X-ray resonant magnetic reflectivity2006In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 300, no 1, p. e371-e374Article in journal (Refereed)
    Abstract [en]

    We have measured and analyzed the X-ray resonant Bragg reflectivity spectra from BCC [Fe/Co]n superstructure near the L2,3 absorption edges of iron. The developed general computer code for the reflectivity calculations from arbitrary anisotropic multilayers allows us to test the different approaches to the treatment of the Bragg reflectivity spectra. We have proved that the observed asymmetry of the spectrum shape at the first-order Bragg peak for the right and left circular polarizations is predominantly caused by the magnetization of the central part of iron layers. The influence of interfaces is almost negligible. The fit of the energy dependence of the integral intensity of the Bragg reflection for the [Fe6/Co6]50 sample gives the value of the magnetic moment of Fe atoms in the central parts of Fe layers ∼2.6 μB, that is larger than the volume value.

  • 9.
    Andreeva, M.A.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Häggström, Lennart
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Lindgren, Bengt
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Kalska, Beata
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Blixt, Anna-Maria
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Kamali-Moghaddan, Saaed
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Nuclear resonant reflectivity investigations of a thin magnetic 57Fe layer adjacent to a superconducting V layer2004In: Hyperfine Interactions, Vol. 156/157, p. 607-Article in journal (Refereed)
  • 10. Andreeva, Marina A
    et al.
    Lindgren, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Standing Waves and Reflectivity from an Ultrathin Layer2002In: JETP Letters, Vol. 76, no 12, p. 704-706Article in journal (Refereed)
  • 11. Bergmark, T.
    et al.
    Byström, O.
    Gålnander, B.
    Johnson, S.
    Johnson, T.
    Lofnes, T.
    Norman, G.
    Peterson, T.
    Rathsman, K.
    Reistad, D.
    Westerberg, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Danared, H.
    Status of the HESR electron cooler design work2006In: EPAC´06, Edenburg, Uk, 26-30 June 2006: Status of the HESR electron cooler design work, 2006Conference paper (Other scientific)
  • 12.
    Björck, Matts
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Interface magnetism in FeNi/Co and Fe/Co superlattices studied by XMCD2005Licentiate thesis, monograph (Other scientific)
  • 13.
    Björck, Matts
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Andersson, Gabriella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lindgren, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Wäppling, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Stanciu, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Element-specific magnetic moment profile in BCC Fe/Co superlattices2004In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 284, p. 273-280Article in journal (Refereed)
    Abstract [en]

    BCC Fe/Co superlattices with individual layer thicknesses in the range of 2–9 monolayers have been investigated byX-ray magnetic circular dichroism in combination with SQUID magnetometry in order to study the magnetic momentdistribution in the superlattices. The magnetic moment for Co was found to remain constant, within 0:1 mB=atom, at1:6 mB=atom for all the superlattices. The Fe atoms at the interface have an enhanced moment of about 3:0 mB=atom. Inaddition, a complex dependence of the size of the moments on the thickness of the Fe layer was found and attributed tointerface roughness effects. Element-specific hysteresis curves were also recorded. These measurements show that themagnetic moments of Fe and Co were, as expected, coupled during reversal of the magnetic moment direction.

  • 14.
    Brucas, Rimantas
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV.
    Hafermann, H.
    Kastnelson, Mikhail
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV.
    Soroka, Inna
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV.
    Eriksson, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV.
    Magnetization and domain structure of bcc Fe81Ni19/Co (001) superlattices2004In: Physical Review, Vol. B 69 (6), p. 064411-Article in journal (Refereed)
  • 15. Bručas, R.
    et al.
    Hafermann, H.
    Katsnelson, M. I.
    Soroka, I.L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Eriksson, O.
    Hjörvarsson, Björgvin
    Magnetic anisotropy and evolution of ground state domain structure in bcc Fe81Ni19/Co (001) superlatticesManuscript (Other (popular science, discussion, etc.))
  • 16. Bručas, R.
    et al.
    Hafermann, H.
    Katsnelson, M. I.
    Soroka, I.L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Eriksson, O.
    Hjörvarsson, Björgvin
    Magnetization and domain structure of bcc Fe81Ni19/Co (001) superlattices2004In: Phys. Rev. B, ISSN 0198-0128, Vol. 69, no 6, p. 064411-Article in journal (Refereed)
  • 17. Bručas, R.
    et al.
    Soroka, I.L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Eriksson, O.
    Hjörvarsson, Björgvin
    Hafermann, H.
    Katsnelson, M. I.
    Magnetization transitions and ground state domain phases in bcc Fe81Ni19/Co superlattices: On interface induced magnetic anisotropyManuscript (Other (popular science, discussion, etc.))
  • 18. Chacon, C.
    et al.
    Johansson, E.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Zlotea, C.
    Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Andersson, Yvonne
    Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Growth and Hydrogen uptake of Mg-Y thin films2005In: Journal of Applied Physics, Vol. 97, p. 104903-Article in journal (Refereed)
    Abstract [en]

    Wedged Mg–Y films with compositions ranging from pure Mg to Mg0.83Y0.17 were grown by dc-magnetron sputtering and hydrogenated. Mg1–xYx forms a substitutional alloy, ranging from 0 to at least 17 at. % in thin films. The c lattice parameter of the film containing 17 at. % of yttrium is determined to be approximatively 1% larger than in pure Mg. Upon exposure to 1 bar of hydrogen at 300 K, the samples switch from shiny metals to colorless semiconductor. Different characteristic hydrogen depth distributions are found for different Y concentrations. At low yttrium contents, a large concentration gradient is observed, with the highest hydrogen concentration close to the Pd/Mg1–xYx interface. For yttrium concentrations larger than 7 at. %, the obtained hydrogen distribution is almost independent of depth. The optical band gap is determined to be 3.6 eV, for all the Y concentrations. The optical transmission is found to decrease for increasing Y content, which is associated with an incomplete hydride formation in the films.

  • 19. Chacon, Cyril
    et al.
    Johansson, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Zlotea, Claudia
    Andersson, Yvonne
    Hjörvarsson, Björgvin
    Growth and hydrogen uptake of Mg-Y thin filmsManuscript (Other (popular science, discussion, etc.))
  • 20. Clarke, S. F.
    et al.
    Rennie, A. R.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Thirtle, P.
    Li, Z, X.
    Thomas, R. K.
    Adsorption of gelatin to a polystyrene/water interface as a function of concentration, pH, and ionic strength2005In: LANGMUIR, Vol. 21 (22), p. 10082-10088Article in journal (Refereed)
  • 21.
    Eriksson, O
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV. Physics V. TEORETISK MAGNETISM.
    Andersson, G
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV. Physics V. Fysik III.
    Karis, O
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Physics IV. Physics V. Fysik V.
    Svedlindh, P
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Department of Physics and Materials Science, Physics III. Physics IV. Physics V.
    Lågdimensionell magnetism; en samlingsplats för experiment, teori och industri2001In: Kosmos 2001, 2001, p. 77-Chapter in book (Other (popular scientific, debate etc.))
  • 22. Garcia-Calderon, R.
    et al.
    Fernandez Barquin, L.
    Marcano, N
    Kalvius, G. M.
    Wagner, F. E.
    Hartmann, Ola
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Wäppling, Roger
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Pankhurst, Q. A.
    Local magnetism in the nanoscale granular alloy Fe13Cu10Ag772006In: Physica B, Vol. 67, p. 374-375Article in journal (Refereed)
  • 23. Gremaud, R.
    et al.
    Borgschulte, A.
    Chacon, C.
    van Mechelen, J. I. m
    Schreuders, H.
    Zuttel, A.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Dam, B.
    Griessen, R.
    Structural and optical properties of Mgx-1Hy gradient thin films: a combinatorial approach2006In: APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, Vol. 84, no (1-2), p. 77-85Article in journal (Refereed)
  • 24.
    Gustavsson, F
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Bertacco, R
    Etgens, V. H
    Marangolo, M
    Eddrief, M
    Photoemission and spin-resolved inverse photoemission studies of thin Fe layers on ZnSe(001)Manuscript (Other (popular science, discussion, etc.))
  • 25.
    Gustavsson, F
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Etgens, V. H
    Marangolo, M
    The effects of anisotropic lattice relaxation on the magnetic anisotropy in Fe/ZnSe(001)In: Phys. Rev. BArticle in journal (Refereed)
  • 26.
    Gustavsson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Properties of Fe/ZnSe Heterostructures: A Step Towards Semiconductor Spintronics2002Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the present thesis, the properties at ferromagnet/semiconductor interfaces, relevant for semiconductor spintronics applications, are addressed. Semiconductor spintronics refers to the possibility of storing information using the electron spin, additional to the electron charge, for enhanced flexibility in nanoscale semiconductor devices.

    The system under focus is the Fe/ZnSe(001) heterostructure, where ZnSe is a wide gap semiconductor ideally compatible with GaAs. The heterostructures are grown on GaAs(001) substrates by molecular beam epitaxy. From various electron-beam based diffraction, spectroscopy and microscopy techniques, it is shown that Fe grows epitaxially and predominantly in a layer-by-layer mode on ZnSe(001) with no presence of chemically reacted phases or interdiffusion.

    An in-plane uniaxial magnetic anisotropy (UMA) is detected for thin Fe films on ZnSe(001) by magnetometry, thus opposing the cubic symmetry of bcc Fe. From first principles calculations, the unidirectional sp3-bonds from ZnSe are shown to induce this uniaxiality. Moreover, an in-plane anisotropic lattice relaxation of Fe is found experimentally, seemingly as a consequence of the sp3-bonds, giving an additional UMA contribution via magneto-elastic coupling. It is proposed that these two effects are responsible for the much-debated UMA observed in Fe/semiconductor structures in general.

    The interface magnetism is probed by x-ray magnetic circular dichroism and Mössbauer spectroscopy. It is found that the magnetic moment at the interface is comparable or even enhanced with respect to the bulk Fe. These two experiments are believed to provide the first unambiguous proof of a persistent bulk magnetic moment at a transition metal/semiconductor interface.

    Spin-polarised transport measurements are performed on Fe/ZnSe/FeCo magnetic tunnel junctions. A magnetoresistance of 16% is found at low temperature, which evidences both the existence of interface spin polarisation, as inferred from the bulk magnetic moment above, and that the spin polarisation can be transmitted across the semiconductor barrier layer.

    List of papers
    1. Structural and transport properties of epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions
    Open this publication in new window or tab >>Structural and transport properties of epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions
    2001 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 18, p. 184422-Article in journal (Refereed) Published
    Abstract [en]

    The use of a semiconductor barrier in heteroepitaxy with ferromagnetic metal electrodes describes a novel type of magnetic tunnel junctions. In this work, epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions have been grown on ZnSe(001) buffered GaAs(001) substrates by molecular beam epitaxy. Alloying a small amount of Co with Fe in the base electrode provides a better seed epilayer for the growth of the ZnSe barrier compared to pure Fe as seen by transmission electron microscopy. Detailed characterization of the FeCo surface was performed by in situ scanning tunneling microscopy and revealed pyramid-shaped defects of up to 60 Å in height distributed on the FeCo surface. Transport measurements on microfabricated tunnel junctions yielded up to 16% magnetoresistance at 10 K and the effect is attributed to spin polarized tunneling across the semiconductor barrier in the energy range of the gap. The observed anomalous character of the magnetoresistance was attributed to conduction through the pyramidal defects in the base FeCo layer.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-89806 (URN)10.1103/PhysRevB.64.184422 (DOI)
    Available from: 2002-04-25 Created: 2002-04-25 Last updated: 2017-12-14Bibliographically approved
    2. Magnetism of the Fe/ZnSe(001) interface
    Open this publication in new window or tab >>Magnetism of the Fe/ZnSe(001) interface
    Show others...
    2002 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 88, no 21, p. 217202-Article in journal (Refereed) Published
    Abstract [en]

    The magnetism of epitaxial ultrathin films of Fe on ZnSe(001) has been investigated by x-ray magnetic circular dichroism down to the submonolayer regime. In contrast to other metallic ferromagnet/semiconductor interfaces, no reduction of the Fe magnetic moment was found at the Fe/ZnSe(001) interface. Furthermore, a significant enhancement of the Fe magnetic moment compared to the bulk value was observed for coverages up to one monolayer in agreement with theoretical predictions. We also demonstrate that the magnetic properties of the Fe/ZnSe(001) interface remain stable against thermal annealing up to 300 degrees C, a prerequisite for the future development of efficient spintronics devices.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-89807 (URN)10.1103/PhysRevLett.88.217202 (DOI)12059497 (PubMedID)
    Available from: 2002-04-25 Created: 2002-04-25 Last updated: 2017-12-14Bibliographically approved
    3. Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
    Open this publication in new window or tab >>Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
    Show others...
    2002 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 2, p. 024405-Article in journal (Refereed) Published
    Abstract [en]

    The interface magnetic properties of Fe/ZnSe heterostructures grown on GaAs(001) by molecular-beam epitaxy have been investigated using conversion electron Mössbauer spectroscopy (CEMS) and macroscopic magnetic measurements. For Fe films thinner than 100 Å an in-plane 〈110〉 uniaxial magnetic anisotropy was found and the magnetization loops could successfully be described by the simple Stoner-Wohlfarth model, which implies that the magnetization reverses only by coherent rotation and jump processes. For the interface analysis, a 5-Å-thick layer of enriched 57Fe was deposited on the ZnSe surface and buried under 20 Å of natural Fe. In this way the 57Fe serves as a local probe of the interface magnetic environment in a bulklike Fe film since the CEMS technique is only sensitive to this isotope of Fe. An interface magnetic moment of 2.18 μB was found and, in relation to 2.2 μB for bulk bcc Fe, this precludes the presence of any interface reactions. Surprisingly, however, the direction of the interface magnetic moment turned out to be reoriented from the [110] direction by almost 30°, an effect that was assumed to arise from the distribution of unidirectional tetrahedral bonds present on the Zn c(2×2) reconstructed ZnSe surface.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-89774 (URN)10.1103/PhysRevB.66.024405 (DOI)
    Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14Bibliographically approved
    4. The effects of anisotropic lattice relaxation on the magnetic anisotropy in Fe/ZnSe(001)
    Open this publication in new window or tab >>The effects of anisotropic lattice relaxation on the magnetic anisotropy in Fe/ZnSe(001)
    (English)In: Phys. Rev. BArticle in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-89809 (URN)
    Available from: 2002-04-25 Created: 2002-04-25 Last updated: 2009-04-30Bibliographically approved
    5. On the unaixial magnetocrystalline anisotropy of metal/semiconductor interfaces; Fe/ZnSe(001)
    Open this publication in new window or tab >>On the unaixial magnetocrystalline anisotropy of metal/semiconductor interfaces; Fe/ZnSe(001)
    (English)In: Phys. Rev. Lett.Article in journal (Refereed) Submitted
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-89810 (URN)
    Available from: 2002-04-25 Created: 2002-04-25 Last updated: 2012-03-29Bibliographically approved
    6. Photoemission and spin-resolved inverse photoemission studies of thin Fe layers on ZnSe(001)
    Open this publication in new window or tab >>Photoemission and spin-resolved inverse photoemission studies of thin Fe layers on ZnSe(001)
    Show others...
    (English)Manuscript (Other (popular science, discussion, etc.))
    Identifiers
    urn:nbn:se:uu:diva-89811 (URN)
    Available from: 2002-04-25 Created: 2002-04-25 Last updated: 2010-01-14Bibliographically approved
  • 27.
    Gustavsson, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    George, J-M
    Etgens, V. H
    Eddrief, M.
    Structural and transport properties of epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 18, p. 184422-Article in journal (Refereed)
    Abstract [en]

    The use of a semiconductor barrier in heteroepitaxy with ferromagnetic metal electrodes describes a novel type of magnetic tunnel junctions. In this work, epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions have been grown on ZnSe(001) buffered GaAs(001) substrates by molecular beam epitaxy. Alloying a small amount of Co with Fe in the base electrode provides a better seed epilayer for the growth of the ZnSe barrier compared to pure Fe as seen by transmission electron microscopy. Detailed characterization of the FeCo surface was performed by in situ scanning tunneling microscopy and revealed pyramid-shaped defects of up to 60 Å in height distributed on the FeCo surface. Transport measurements on microfabricated tunnel junctions yielded up to 16% magnetoresistance at 10 K and the effect is attributed to spin polarized tunneling across the semiconductor barrier in the energy range of the gap. The observed anomalous character of the magnetoresistance was attributed to conduction through the pyramidal defects in the base FeCo layer.

  • 28.
    Gustavsson, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Nordström, E.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Etgens, V. H.
    Eddrief, M.
    Sjöstedt, Elisabeth
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Wäppling, R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    George, J. M.
    Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy2002In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 2, p. 024405-Article in journal (Refereed)
    Abstract [en]

    The interface magnetic properties of Fe/ZnSe heterostructures grown on GaAs(001) by molecular-beam epitaxy have been investigated using conversion electron Mössbauer spectroscopy (CEMS) and macroscopic magnetic measurements. For Fe films thinner than 100 Å an in-plane 〈110〉 uniaxial magnetic anisotropy was found and the magnetization loops could successfully be described by the simple Stoner-Wohlfarth model, which implies that the magnetization reverses only by coherent rotation and jump processes. For the interface analysis, a 5-Å-thick layer of enriched 57Fe was deposited on the ZnSe surface and buried under 20 Å of natural Fe. In this way the 57Fe serves as a local probe of the interface magnetic environment in a bulklike Fe film since the CEMS technique is only sensitive to this isotope of Fe. An interface magnetic moment of 2.18 μB was found and, in relation to 2.2 μB for bulk bcc Fe, this precludes the presence of any interface reactions. Surprisingly, however, the direction of the interface magnetic moment turned out to be reoriented from the [110] direction by almost 30°, an effect that was assumed to arise from the distribution of unidirectional tetrahedral bonds present on the Zn c(2×2) reconstructed ZnSe surface.

  • 29. Henderson, M. J.
    et al.
    Hawley, A. M.
    Rennie, Adrian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Gibaud, A.
    Bardeau, J-F.
    White, J. W.
    Titanium Oxide Film Self-Assembled at the Air/Water Interface’2006In: Chemical PhysicsArticle in journal (Refereed)
  • 30.
    Johansson, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Synthesis and Characterisation of Potential Hydrogen Storage Materials2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dissociative and non-dissociative hydrogen uptake in carbon nanostructures and metallic films were investigated by measurements and analysis of solubility isotherms. The total, non-dissociative, uptake for multi-walled nano-barrels and amorphous nanoporous carbon was determined to be 6.2 and 4.2 wt. % respectively at 77 K and the adsorption energies (at lowest coverage) -7.2 and -4.2 kJ/mol. At 298 K the H-uptake was negligible.

    At low concentrations the H-uptake of Nb-films is strongly affected by the film thickness. For thicknesses less then about 31 nm, the absorption energy was found to be temperature dependent. Such changes have not been observed in Nb films before. The presence of multiple absorption energies was shown to limit the possibility to obtain relevant absorption and interaction energies by traditional Sievert's and van 't Hoff analysis.

    The Mg1-xNix system (0<0.43) was investigated with respect to the hydrogen uptake. For Mg2Ni the hydrogen uptake, at an external hydrogen pressure of 1 bar, is close to 1.33 H/M (Mg2NiH4). The enthalpy of formation is smaller in the film as compared to bulk material. The changes in the absorption energy are caused by the adhesion to the substrate as well as the nanocrystallinity of the absorbing layers. The optical band gap of Mg2NiH4 was determined to be 2.4 eV.

    In Mg1-xYx (0<0.17) it was found that the Y-concentration limits the hydrogen uptake at 1 bar. However, the kinetics of the uptake improves substantially with a minimum of 7 at.% of Y. For Mg-Y the optical band gap (3.6 eV) is independent of Y concentration within the concentration range investigated, while the transmittance decreases with increasing Y content.

    List of papers
    1. Hydrogen in carbon nanostructures
    Open this publication in new window or tab >>Hydrogen in carbon nanostructures
    2002 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, Vol. 330-332, p. 670-675Article in journal (Refereed) Published
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-92034 (URN)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2012-03-07Bibliographically approved
    2. Solubility of hydrogen at low concentrations in thin epitaxial Nb(110) films
    Open this publication in new window or tab >>Solubility of hydrogen at low concentrations in thin epitaxial Nb(110) films
    2004 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, Vol. 16, p. 1165-1174Article in journal (Refereed) Published
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-92035 (URN)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2012-03-07Bibliographically approved
    3. Hydrogen uptake and optical properties of sputtered Mg-Ni thin films
    Open this publication in new window or tab >>Hydrogen uptake and optical properties of sputtered Mg-Ni thin films
    Show others...
    (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984Article in journal (Refereed) Submitted
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-92036 (URN)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2012-03-07Bibliographically approved
    4. Structural and optical properties of Mg2NiHx switchable mirrors upon hydrogen loading
    Open this publication in new window or tab >>Structural and optical properties of Mg2NiHx switchable mirrors upon hydrogen loading
    Show others...
    2004 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 70, p. 165411-Article in journal (Refereed) Published
    Abstract [en]

    The structural, thermodynamic and optical properties of Mg2Ni thin films covered with Pd are investigatedupon exposure to hydrogen. Similar to bulk, thin films of metallic Mg2Ni take up 4 hydrogen per formula unitand semiconducting transparent Mg2NiH4−d is formed. The dielectric function e˜ of Mg2Ni and fully loadedMg2NiH4−d is determined from reflection and transmission measurements using a Drude-Lorentz parametrization.Besides the two “normal” optical states of a switchable mirror—metallic reflecting and semiconductingtransparent—Mg2NiHx exhibit a third “black” state at intermediate hydrogen concentrations with low reflectionand essentially zero transmission. This state originates from a subtle interplay of the optical properties of theconstituent materials and a self-organized double layering of the film during loading. Mg2NiH4−d preferentiallynucleates at the film/substrate interface and not—as intuitively expected—close to the catalytic Pd cappinglayer. Using e˜Mg2Ni and e˜Mg2NiH4and this loading sequence, the optical response at all hydrogen concentrationscan be described quantitatively. The uncommon hydrogen loading sequence is confirmed by x-ray diffractionand hydrogen profiling using the resonant nuclear reaction 1Hs15N,agd12C. Pressure-composition isothermssuggest that

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-92037 (URN)10.1103/PhysRevB.70.165411 (DOI)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2017-12-14Bibliographically approved
    5. Hydrogen solubility at low concentrations in sputtered Mg-Ni thin films
    Open this publication in new window or tab >>Hydrogen solubility at low concentrations in sputtered Mg-Ni thin films
    (English)Manuscript (Other (popular science, discussion, etc.))
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-92038 (URN)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2012-03-07Bibliographically approved
    6. Growth and hydrogen uptake of Mg-Y thin films
    Open this publication in new window or tab >>Growth and hydrogen uptake of Mg-Y thin films
    Show others...
    (English)Manuscript (Other (popular science, discussion, etc.))
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-92039 (URN)
    Available from: 2004-09-01 Created: 2004-09-01 Last updated: 2012-01-27Bibliographically approved
  • 31.
    Johansson, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Chacon, Cyril
    Hjörvarsson, Björgvin
    Hydrogen solubility at low concentrations in sputtered Mg-Ni thin filmsManuscript (Other (popular science, discussion, etc.))
  • 32.
    Johansson, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Chacon, Cyril
    Zlotea, Claudia
    Andersson, Yvonne
    Hjörvarsson, Björgvin
    Hydrogen uptake and optical properties of sputtered Mg-Ni thin filmsIn: Journal of Physics: Condensed Matter, ISSN 0953-8984Article in journal (Refereed)
  • 33.
    Johansson, Emil
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Chacon, Cyril
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Zlotea, Claudia
    Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Andersson, Yvonne
    Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry. oorganisk kemi.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III. Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Hydrogen uptake and optical properties of sputtered Mg-Ni thin films2004In: Journal of Physics: Condensed Matter, Vol. 16, p. 7649-Article in journal (Refereed)
    Abstract [en]

    The hydrogen uptake and distribution in wedged Mg–Ni films, with composition ranging from Mg0.85Ni0.15 to Mg0.55Ni0.45, were investigated. Upon hydrogen loading at 298 K these films undergo a transition from a mirror-like metallic to a semiconducting transparent state. After exposure to a hydrogen pressure of 1 bar, the samples exhibit large variation in optical appearance, ranging from a pale yellowish (Mg rich side) to a brownish shade (Ni rich side). The change in the effective optical band gap Egeff as a function of sample composition and hydrogen concentration was determined; it showed changes from 3.6 eV in the Ni poor domain to 2.4 eV in the Ni rich domain. Composition analysis using the 15N nuclear resonance method showed close to homogeneous hydrogen distribution throughout the film and close to linear increase in the hydrogen uptake with increasing Mg content. The thermal stability of the films is limited; annealing above 393 K results in significant redistribution of the constituents. Mg is enriched at the surface, reacting with Pd and thereby degrading the capping layer through the formation of Mg6Pd and MgO, as determined by x-ray diffraction, x-ray photoelectron spectroscopy and Rutherford backscattering studies. This redistribution results in a severe decrease of the hydrogen uptake rate, as monitored by in situ resistivity measurements.

  • 34.
    Johansson, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Hjörvarsson, Björgvin
    Ekström, Tommy
    Jacob, Michael
    Hydrogen in carbon nanostructures2002In: Journal of Alloys and Compounds, ISSN 0925-8388, Vol. 330-332, p. 670-675Article in journal (Refereed)
  • 35.
    Johansson, Emil
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Olsson, Stefan
    Chacon, Cyril
    Hjörvarsson, Björgvin
    Solubility of hydrogen at low concentrations in thin epitaxial Nb(110) films2004In: Journal of Physics: Condensed Matter, ISSN 0953-8984, Vol. 16, p. 1165-1174Article in journal (Refereed)
  • 36.
    Johansson, Emil
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Olsson, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Chacon, Cyril
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Hjörvarsson, Björgvin
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Solubility of hydrogen at low concentrations in thin epitaxial Nb(110) films2004In: JOURNAL OF PHYSICS-CONDENSED MATTER, Vol. 16 (8), p. 1165-1174Article in journal (Refereed)
  • 37. Kalvius, G. M.
    et al.
    Hartmann, Ola
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Noakes, D. R.
    Wagner, F. E.
    Wäppling, Roger
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Zimmerman, U.
    Baines, Ch.
    Krimmel, A.
    Tsurkan, V.
    Loidl, A
    A É SR magnetic study of frustrated FeSc2S4 and MnSc2S42006In: Physica B, Vol. 378-380, p. 592-Article in journal (Refereed)
  • 38. Kalvius, G. M.
    et al.
    Noakes, D. R.
    Wäppling, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Marcano, N.
    Schreier, E.
    Hartman, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Rössler, U. K.
    Nenkov, K.
    Müller, K-H
    Idzikowski, B.
    Study of magnetic clusters in granular CoxCu1- x2008In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 77, no 2, p. 025705-Article in journal (Refereed)
    Abstract [en]

    Samples of CoxCu1-x (x = 0.05, 0.02 and 0.01) produced by melt spinning and subsequent annealing were studied by muon spin rotation/relaxation (mu SR) spectroscopy with the aim to gain information on the dependence of the local magnetic properties like the magnitude, the distribution and the temporal behavior of the magnetic field at the muon site as function of Co concentration. In addition, we investigated for Co0.02Cu0.98 the changes in mu SR response as function of annealing times and temperatures. In all alloys, a spin-glass-like magnetic cluster state was seen well below the susceptibility cusp temperature. Above this temperature, cluster spin dynamics sets in but with low fluctuation rates even at high temperatures reflecting the presence of strong cluster - cluster couplings. A free paramagnetic cluster state is not formed. Spin dynamic properties are different for the x = 0(05 and 0.02 compounds and the x = 0(01 alloy. In the former compounds, the coexistence of a slower and a faster fluctuating fraction is found, arising from a non-uniform cluster size distribution or a non-random spatial distribution of clusters. In the latter compound, the spin dynamical state is homogeneous, but shows an unusual mu SR response requiring the presence of simultaneous fluctuations in spin orientation and moment magnitude. It further points to the presence of a partial loss of magnetic clusters. The variation of annealing times and temperatures for Co0.02Cu0.98 influences details of mu SR spectral parameters but leaves the overall response the same.

  • 39.
    Kamali, Saeed
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Bergman, A.
    Andersson, Gabriella
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Stanciu, V.
    Häggström, Lennart
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics III.
    Local magnetic effects of interface aloying in Fe/Co superlattices2006In: J. Phys.: Condens. Matter, Vol. 18, p. 5807-5824Article in journal (Refereed)
  • 40.
    Kamali, Saeed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Bergman, Anders
    Andersson, Gabriella
    Stanciu, Victor
    Häggström, Lennart
    Local Magnetic Effects of Surface Alloying in Fe/Co SuperlatticesManuscript (Other (popular science, discussion, etc.))
  • 41.
    Kamali, Saeed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Blixt, Anna-Maria
    Häggström, Lennart
    Wäppling, Roger
    Stanciu, Victor
    Nordblad, Per
    Magnetic Properties of a Fe0.82Ni0.18/V(001) Superlattice Studied by Mössbauer Spectroscopy2004In: Journal of Magnetism and Magnetic Materials, Vol. 272-276, p. 1263-1265Article in journal (Refereed)
  • 42.
    Kamali, Saeed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Wäppling, Roger
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.
    Characterization of iron oxide nanoparticles by Mössbauer spectroscopy2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 2, p. 721-723Article in journal (Refereed)
    Abstract [en]

    Small particles of iron oxides, nominally 7 nm and 13 nm in diameter, have been studied by 57Fe Mössbauer spectroscopy in the temperature range 4 K to room temperature. The Mössbauer spectra show, at high temperature, relaxational behaviour in agreement with the superparamagnetism expected. At low temperature the spin motion becomes slower and, finally, blocked. There are also indications that the material is non-stoichiometric.

  • 43.
    Kamali, Saeed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics III.