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Eriksson, Olle
Alternative names
Publications (10 of 463) Show all publications
Poluektov, M., Eriksson, O. & Kreiss, G. (2018). Coupling atomistic and continuum modelling of magnetism. Computer Methods in Applied Mechanics and Engineering, 329, 219-253.
Open this publication in new window or tab >>Coupling atomistic and continuum modelling of magnetism
2018 (English)In: Computer Methods in Applied Mechanics and Engineering, ISSN 0045-7825, E-ISSN 1879-2138, Vol. 329, 219-253 p.Article in journal (Refereed) Published
National Category
Computational Mathematics Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-331985 (URN)10.1016/j.cma.2017.10.010 (DOI)
Projects
eSSENCE
Available from: 2017-10-16 Created: 2017-10-20 Last updated: 2017-11-08Bibliographically approved
Kádas, K., Iusan, D., Hellsvik, J., Cedervall, J., Berastegui, P., Sahlberg, M., . . . Eriksson, O. (2017). AlM2B2 (M =Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials. Journal of Physics: Condensed Matter, 29(15), Article ID 155402.
Open this publication in new window or tab >>AlM2B2 (M =Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials
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2017 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 15, 155402Article in journal (Refereed) Published
Abstract [en]

Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono-and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keyword
nanolaminated ternary borides, phase stability, elastic constants, hardness, scanning electron microscopy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-320624 (URN)10.1088/1361-648X/aa602a (DOI)000397921600002 ()28192279 (PubMedID)
Funder
Swedish Research Council
Available from: 2017-08-15 Created: 2017-08-15 Last updated: 2017-08-15Bibliographically approved
Salikhov, R., Reichel, L., Zingsem, B., Abrudan, R., Edström, A., Thonig, D., . . . Wiedwald, U. (2017). Enhanced spin–orbit coupling in tetragonally strained Fe–Co–B films. Journal of Physics: Condensed Matter, 9(27), Article ID 275802.
Open this publication in new window or tab >>Enhanced spin–orbit coupling in tetragonally strained Fe–Co–B films
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2017 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 9, no 27, 275802Article in journal (Refereed) Published
Abstract [en]

Tetragonally strained interstitial Fe-Co-B alloys were synthesized as epitaxial films grown on a 20 nm thick Au0.55Cu0.45 buffer layer. Different ratios of the perpendicular to in-plane lattice constant c/a = 1.013, 1.034 and 1.02 were stabilized by adding interstitial boron with different concentrations 0, 4, and 10 at.%, respectively. Using ferromagnetic resonance (FMR) and x-ray magnetic circular dichroism (XMCD) we found that the total orbital magnetic moment significantly increases with increasing c/a ratio, indicating that reduced crystal symmetry and interstitial B leads to a noticeable enhancement of the effect of spin-orbit coupling (SOC) in the Fe-Co-B alloys. First-principles calculations reveal that the increase in orbital magnetic moment mainly originates from B impurities in octahedral position and the reduced symmetry around B atoms. These findings offer the possibility to enhance SOC phenomena-namely the magnetocrystalline anisotropy and the orbital moment-by stabilizing anisotropic strain by doping 4 at.% B. Results on the influence of B doping on the Fe-Co film microstructure, their coercive field and magnetic relaxation are also presented.

Keyword
magnetism, spin-orbit, magnetic anisotropy, FRM, XMCD, DFT
National Category
Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-304518 (URN)10.1088/1361-648X/aa7498 (DOI)000403326600001 ()28530633 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 280670Swedish Research Council
Note

Title in list of papers in Thesis: Enhanced and Tunable Spin-Orbit Coupling in tetragonally Strained Fe-Co-B Films

Available from: 2016-10-06 Created: 2016-10-06 Last updated: 2017-08-22Bibliographically approved
Ivanov, S. A., Bush, A. A., Ritter, C., Behtin, M. A., Cherepanov, V. M., Autieri, C., . . . Mathieu, R. (2017). Evolution of the structural and multiferroic properties of PbFe2/3W1/3O3 ceramics upon Mn-doping. Materials Chemistry and Physics, 187, 218-232.
Open this publication in new window or tab >>Evolution of the structural and multiferroic properties of PbFe2/3W1/3O3 ceramics upon Mn-doping
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2017 (English)In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 187, 218-232 p.Article in journal (Refereed) Published
Abstract [en]

The perovskite system Pb(Fe1-xMnx)(2/3)W1/3O3 (0 <= x <= 1, PFMWO) has been prepared by conventional solid-state reaction under different sintering conditions. Structures and phase composition as well as thermal, magnetic and dielectric properties of the compounds have been systematically investigated experimentally and by first-principles density functional calculations. A clean perovskite phase is established at room temperature for compositions 0 <= x <= 0.4. Rietveld refinements of X-ray and neutron powder diffraction patterns demonstrate that the compounds crystallize in space group Pm-3m (0 <= x <= 0.4). The degree of ordering of the Fe and W/Mn cations was found to depend on the concentration of Mn. First-principles calculations suggest that the structural properties of PFMWO are strongly influenced by the Jahn Teller effect. The PFMWO compounds behave as relaxor ferroelectrics at weak Mn-doping with a dielectric constant that rapidly decreases with increasing Mn content. A low temperature antiferromagnetic G-type order with propagation vector k = (1/2,1/2,1/2) is derived from neutron powder diffraction data for the samples with x <= 0.4. However with increasing doping concentration, the magnetic order is perturbed. First principles calculations show that the dominant exchange coupling is antiferromagnetic and occurs between nearest neighbor Fe atoms. When the system is doped with Mn, a relatively weak ferromagnetic (FM) interaction between Fe and Mn atoms emerges. However, due to the presence of this FM interaction, the correlation length of the magnetic order is greatly shortened already at rather low doping levels.

Keyword
Oxides, Dielectric properties, Magnetic properties, Magnetic structures
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-316943 (URN)10.1016/j.matchemphys.2016.12.003 (DOI)000392786900026 ()
Funder
Swedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Knut and Alice Wallenberg FoundationCarl Tryggers foundation , CTS 12:419 13:413
Available from: 2017-03-09 Created: 2017-03-09 Last updated: 2017-11-29Bibliographically approved
Keshavarz, S., Kvashnin, Y. O., Rodrigues, D. C. M., Pereiro, M., Di Marco, I., Autieri, C., . . . Eriksson, O. (2017). Exchange interactions of CaMnO3 in the bulk and at the surface. Physical Review B Condensed Matter, 95, Article ID 115120.
Open this publication in new window or tab >>Exchange interactions of CaMnO3 in the bulk and at the surface
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2017 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 95, 115120Article in journal (Refereed) Published
Abstract [en]

We present electronic and magnetic properties of CaMnO3 (CMO) as obtained from ab initio calculations. We identify the preferable magnetic order by means of density functional theory plus Hubbard U calculations and extract the effective exchange parameters (Jij ' s) using the magnetic force theorem. We find that the effects of geometrical relaxation at the surface as well as the change of crystal field are very strong and are able to influence the lower-energymagnetic configuration. In particular, our analysis reveals that the exchange interaction between the Mn atoms belonging to the surface and the subsurface layers is very sensitive to the structural changes. An earlier study [A. Filippetti and W. E. Pickett, Phys. Rev. Lett. 83, 4184 (1999)] suggested that this coupling is ferromagnetic and gives rise to the spin-flip (SF) process on the surface of CMO. In our work, we confirm their finding for an unrelaxed geometry, but once the structural relaxations are taken into account, this exchange coupling changes its sign. Thus, we suggest that the surface of CMO should have the same G-type antiferromagnetic order as in the bulk. Finally, we show that the suggested SF can be induced in the system by introducing an excess of electrons.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-319934 (URN)10.1103/PhysRevB.95.115120 (DOI)000396008300003 ()
Funder
Swedish Research CouncileSSENCE - An eScience CollaborationKnut and Alice Wallenberg Foundation
Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2017-11-29Bibliographically approved
de Melo Rodrigues, D. C., Pereiro, M., Bergman, A., Eriksson, O. & Klautau, A. B. (2017). First-principles theory of electronic structure and magnetism of Cr nano-islands on Pd(111). Journal of Physics: Condensed Matter, 29(2), Article ID 025807.
Open this publication in new window or tab >>First-principles theory of electronic structure and magnetism of Cr nano-islands on Pd(111)
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2017 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 2, 025807Article in journal (Refereed) Published
Abstract [en]

We report on the electronic structure, magnetic moments and exchange interactions of one-and two-dimensional Cr clusters on a Pd(1 1 1) substrate, using a real-space method based on density functional theory in the local spin density approximation. We find in general that for the investigated clusters, the magnetic moments are sizeable and almost entirely of spin-character. We demonstrate that the interactions in general are dominated by nearest-neighbor antiferromagnetic Heisenberg form, which implies that Cr on Pd(1 1 1) forms an ideal model system, in which clusters of almost any shape and size can be investigated from a Heisenberg Hamiltonian, using a nearest-neighbor exchange model. We have also found that complex magnetic structures can be realized for linear chains of Cr, due to a competition between exchange interaction and a weaker Dzyaloshinskii-Moriya interaction.

Keyword
nanomagnetism, electronic structure, metallic nanowires
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-311166 (URN)10.1088/0953-8984/29/2/025807 (DOI)000388615900007 ()
Funder
Knut and Alice Wallenberg Foundation, 2013.0020 2012.0031Swedish Research Council
Available from: 2016-12-22 Created: 2016-12-22 Last updated: 2017-11-29Bibliographically approved
Thonig, D., Eriksson, O. & Pereiro, M. (2017). Magnetic moment of inertia within the torque-torque correlation model. Scientific Reports, 7, Article ID 931.
Open this publication in new window or tab >>Magnetic moment of inertia within the torque-torque correlation model
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 931Article in journal (Refereed) Published
Abstract [en]

An essential property of magnetic devices is the relaxation rate in magnetic switching which strongly depends on the energy dissipation. This is described by the Landau-Lifshitz-Gilbert equation and the well known damping parameter, which has been shown to be reproduced from quantum mechanical calculations. Recently the importance of inertia phenomena have been discussed for magnetisation dynamics. This magnetic counterpart to the well-known inertia of Newtonian mechanics, represents a research field that so far has received only limited attention. We present and elaborate here on a theoretical model for calculating the magnetic moment of inertia based on the torque-torque correlation model. Particularly, the method has been applied to bulk itinerant magnets and we show that numerical values are comparable with recent experimental measurements. The theoretical analysis shows that even though the moment of inertia and damping are produced by the spin-orbit coupling, and the expression for them have common features, they are caused by very different electronic structure mechanisms. We propose ways to utilise this in order to tune the inertia experimentally, and to find materials with significant inertia dynamics.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-322156 (URN)10.1038/s41598-017-01081-z (DOI)000399534300002 ()28424483 (PubMedID)
Funder
Swedish Research CouncileSSENCE - An eScience Collaboration
Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-05-17Bibliographically approved
Hedlund, D., Cedervall, J., Edström, A., Werwinski, M., Kontos, S., Eriksson, O., . . . Gunnarsson, K. (2017). Magnetic properties of the Fe5SiB2−Fe5PB2 system. Physical Review B, 96(9), Article ID 094433.
Open this publication in new window or tab >>Magnetic properties of the Fe5SiB2−Fe5PB2 system
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2017 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 9, 094433Article in journal (Refereed) Published
Abstract [en]

The magnetic properties of the compound Fe5Si1−xPxB2 have been studied, with a focus on the Curie temperature TC, saturation magnetization MS, and magnetocrystalline anisotropy. Field and temperature dependent magnetization measurements were used to determine TC(x) and MS(x). The saturation magnetization at 10 K (300 K) is found to monotonically decrease from 1.11MA/m (1.03MA/m) to 0.97MA/m (0.87MA/m), as x increases from 0 to 1. The Curie temperature is determined to be 810 and 615 K in Fe5SiB2 and Fe5PB2, respectively. The highest TC is observed for x=0.1, while it decreases monotonically for larger x. The Curie temperatures have also been theoretically determined to be 700 and 660 K for Fe5SiB2 and Fe5PB2, respectively, using a combination of density functional theory and Monte Carlo simulations. The magnitude of the effective magnetocrystalline anisotropy was extracted using the law of approach to saturation, revealing an increase with increasing phosphorus concentration. Low-field magnetization vs temperature results for x=0,0.1,0.2 indicate that there is a transition from easy-axis to easy-plane anisotropy with decreasing temperature.

Place, publisher, year, edition, pages
American Physical Society, 2017
Keyword
Magnetism, Ferromagnetism, First-principle calculations, Magnetic interactions, Magnetic order parameter, Magnetic phase transition
National Category
Condensed Matter Physics Engineering and Technology
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-330463 (URN)10.1103/PhysRevB.96.094433 (DOI)000411975700001 ()
Funder
Swedish Research CouncilGöran Gustafsson Foundation for Research in Natural Sciences and MedicineKnut and Alice Wallenberg Foundation, 2013.0020, 2012.0031EU, Horizon 2020
Available from: 2017-09-29 Created: 2017-09-29 Last updated: 2017-12-20Bibliographically approved
Chimata, R., Delczeg-Czirjak, E. K., Szilva, A., Cardias, R., Kvashnin, Y., Pereiro, M., . . . Eriksson, O. (2017). Magnetism and ultrafast magnetization dynamics of Co and CoMn alloys at finite temperature. Physical review B, 95(21), Article ID 214417.
Open this publication in new window or tab >>Magnetism and ultrafast magnetization dynamics of Co and CoMn alloys at finite temperature
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2017 (English)In: Physical review B, ISSN 2469-9950, Vol. 95, no 21, 214417Article in journal (Refereed) Published
Abstract [en]

Temperature-dependent magnetic experiments such as pump-probe measurements generated by a pulsed laser have become a crucial technique for switching the magnetization in the picosecond time scale. Apart from having practical implications on the magnetic storage technology, the research field of ultrafast magnetization poses also fundamental physical questions. To correctly describe the time evolution of the atomic magnetic moments under the influence of a temperature-dependent laser pulse, it remains crucial to know if the magnetic material under investigation has magnetic excitation spectrum that is more or less dependent on the magnetic configuration, e.g., as reflected by the temperature dependence of the exchange interactions. In this paper, we demonstrate from first-principles theory that the magnetic excitation spectra in Co in fcc, bcc, and hcp structures are nearly identical in a wide range of noncollinear magnetic configurations. This is a curious result of a balance between the size of the magnetic moments and the strength of the Heisenberg exchange interactions, that in themselves vary with configuration, but put together in an effective spin Hamiltonian results in a configuration-independent effective model. We have used such a Hamiltonian, together with ab initio calculated damping parameters, to investigate the magnon dispersion relationship as well as ultrafast magnetization dynamics of Co and Co-rich CoMn alloys.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-308321 (URN)10.1103/PhysRevB.95.214417 (DOI)000404015400003 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation, 2013.0020, 2012.0031StandUp
Available from: 2016-11-24 Created: 2016-11-24 Last updated: 2017-09-21Bibliographically approved
Reichel, L., Edström, A., Pohl, D., Rusz, J., Eriksson, O., Schultz, L. & Fähler, S. (2017). On the origin of perpendicular magnetic anisotropy in strained Fe-Co(-X) films. Journal of Physics D: Applied Physics, 50(4), Article ID 045003.
Open this publication in new window or tab >>On the origin of perpendicular magnetic anisotropy in strained Fe-Co(-X) films
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2017 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 4, 045003Article in journal (Refereed) Published
Abstract [en]

Very high magnetic anisotropies have been theoretically predicted for strained Fe-Co(-X) and indeed several experiments on epitaxial thin films seemed to confirm strain induced anisotropy enhancement. This study presents a critical analysis of the different contributions to perpendicular anisotropy: volume, interface and surface anisotropies. Tracing these contributions, thickness series of single layer films as well as multilayers with Au-Cu buffers/interlayers of different lattice parameters have been prepared. The analysis of their magnetic anisotropy reveals a negligible influence of the lattice parameter of the buffer. Electronic effects, originating from both, the Au-Cu interface and the film surface, outrange the elastic effects. Surface anisotropy, however, exceeds the interface anisotropy by more than a factor of three. A comparison with results from Density Functional Theory suggests, that the experimentally observed strong perpendicular surface anisotropy originates from a deviation from an ideal oxide-free surface. Accordingly, tailored Fe-Co-X/oxideinterfaces may open a route towards high anisotropy in rare-earth free materials.

National Category
Physical Sciences Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-304662 (URN)10.1088/1361-6463/aa51af (DOI)000394089800001 ()
Funder
EU, FP7, Seventh Framework Programme
Available from: 2016-10-06 Created: 2016-10-06 Last updated: 2017-11-30Bibliographically approved
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