uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Eriksson, Olle
Alternative names
Publications (10 of 483) Show all publications
Koumpouras, K., Yudin, D., Adelmann, C., Bergman, A., Eriksson, O. & Pereiro, M. (2018). A majority gate with chiral magnetic solitons. Journal of Physics: Condensed Matter, 30(37), Article ID 375801.
Open this publication in new window or tab >>A majority gate with chiral magnetic solitons
Show others...
2018 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 30, no 37, article id 375801Article in journal (Refereed) Published
Abstract [en]

In magnetic materials, nontrivial spin textures may emerge due to the competition among different types of magnetic interactions. Among such spin textures, chiral magnetic solitons represent topologically protected spin configurations with particle-like properties. Based on atomistic spin dynamics simulations, we demonstrate that these chiral magnetic solitons are ideal to use for logical operations, and we demonstrate the functionality of a three- input majority gate, in which the input states can be controlled by applying an external electromagnetic field or spin-polarized currents. One of the main advantages of the proposed device is that the input and output signals are encoded in the chirality of solitons, that may be moved, allowing to perform logical operations using only minute electric currents. As an example we illustrate how the three input majority gate can be used to perform logical relations, such as Boolean AND and OR.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2018
Keywords
magnonics, majority gate, solitons, spin dynamics, magnetic nanodevices
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-362096 (URN)10.1088/1361-648X/aad82f (DOI)000442630600001 ()30079893 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, 2013.0020Knut and Alice Wallenberg Foundation, 2012.0031Swedish Research CouncileSSENCE - An eScience Collaboration
Available from: 2018-10-03 Created: 2018-10-03 Last updated: 2018-10-03Bibliographically approved
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, p. 219-253Article 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)000422806100010 ()
Projects
eSSENCE
Available from: 2017-10-16 Created: 2017-10-20 Last updated: 2018-05-11Bibliographically approved
Paul, S., Iusan, D., Thunström, P., Kvashnin, Y., Hellsvik, J., Pereiro, M., . . . Eriksson, O. (2018). Investigation of the spectral properties and magnetism of BiFeO3 by dynamical mean-field theory. Physical Review B, 97(12), Article ID 125120.
Open this publication in new window or tab >>Investigation of the spectral properties and magnetism of BiFeO3 by dynamical mean-field theory
Show others...
2018 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 12, article id 125120Article in journal (Refereed) Published
Abstract [en]

Using the local density approximation plus dynamical mean-field theory (LDA+DMFT), we have computed the valence-band photoelectron spectra and magnetic excitation spectra of BiFeO3, one of the most studied multiferroics. Within the DMFT approach, the local impurity problem is tackled by the exact diagonalization solver. The solution of the impurity problem within the LDA+DMFT method for the paramagnetic and magnetically ordered phases produces result in agreement with the experimental data on electronic and magnetic structures. For comparison, we also present results obtained by the LDA+U approach which is commonly used to compute the physical properties of this compound. Our LDA+DMFT derived electronic spectra match adequately with the experimental hard x-ray photoelectron spectroscopy and resonant photoelectron spectroscopy for Fe 3d states, whereas the LDA+U method fails to capture the general features of the measured spectra. This indicates the importance of accurately incorporating the dynamical aspect of electronic correlation among Fe 3d orbitals to reproduce the experimental excitation spectra. Specifically, the LDA+DMFT derived density of states exhibits a significant amount of Fe 3d states at the position of Bi lone pairs, implying that the latter are not alone in the spectral scenario. This fact might modify our interpretation about the origin of ferroelectric polarization in this material. Our study demonstrates that the combination of orbital cross sections for the constituent elements and broadening schemes for the spectral functions are crucial to explain the detailed structures of the experimental electronic spectra. Our magnetic excitation spectra computed from the LDA+DMFT result conform well with the inelastic neutron scattering data.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-351431 (URN)10.1103/PhysRevB.97.125120 (DOI)000427602000002 ()
Funder
Swedish Research CouncilCarl Tryggers foundation
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-06-01Bibliographically approved
Rodrigues, D. C. M., B Klautau, A., Edström, A., Rusz, J., Nordström, L., Pereiro, M., . . . Eriksson, O. (2018). Magnetic anisotropy in permalloy: hidden quantum mechanical features. Physical Review B, 97(22), Article ID 224402.
Open this publication in new window or tab >>Magnetic anisotropy in permalloy: hidden quantum mechanical features
Show others...
2018 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 22, article id 224402Article in journal (Refereed) Published
Abstract [en]

By means of relativistic, first principles calculations, we investigate the microscopic origin of the vanishingly low magnetic anisotropy of Permalloy, here proposed to be intrinsically related to the local symmetries of the alloy. It is shown that the local magnetic anisotropy of individual atoms in Permalloy can be several orders of magnitude larger than that of the bulk sample and 5–10 times larger than that of elemental Fe or Ni. We furthermore show that locally there are several easy axis directions that are favored, depending on local composition. The results are discussed in the context of perturbation theory, applying the relation between magnetic anisotropy and orbital moment. Permalloy keeps its pronounced soft ferromagnetic nature due to the exchange energy to be larger than the magnetocrystalline anisotropy. Our results shine light on the magnetic anisotropy of permalloy and of magnetic materials in general, and in addition enhance the understanding of pump-probe measurements and ultrafast magnetization dynamics.

Keywords
Permalloy, Orbital Anisotropy, Anisotropy Energy
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-319925 (URN)10.1103/PhysRevB.97.224402 (DOI)000434015300004 ()
Funder
Knut and Alice Wallenberg Foundation, 2012.0031Knut and Alice Wallenberg Foundation, 2013.0020Swedish Research CouncileSSENCE - An eScience CollaborationStandUp
Available from: 2017-04-11 Created: 2017-04-11 Last updated: 2018-09-14Bibliographically approved
Shaw, J. M., Delczeg-Czirjak, E. K., Edwards, E. R. J., Kvashnin, Y., Thonig, D., Schoen, M. A. W., . . . Nembach, H. T. (2018). Magnetic damping in sputter-deposited Co2MnGe Heusler compounds with A2, B2, and L2(1) orders: Experiment and theory. Physical Review B, 97(9), Article ID 094420.
Open this publication in new window or tab >>Magnetic damping in sputter-deposited Co2MnGe Heusler compounds with A2, B2, and L2(1) orders: Experiment and theory
Show others...
2018 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 97, no 9, article id 094420Article in journal (Refereed) Published
Abstract [en]

We show that very low values of the magnetic damping parameter can be achieved in sputter deposited polycrystalline films of Co2MnGe annealed at relatively low temperatures ranging from 240 degrees C to 400 degrees C. Damping values as low as 0.0014 are obtained with an intrinsic value of 0.0010 after spin-pumping contributions are considered. Of importance to most applications is the low value of inhomogeneous linewidth that yields measured linewidths of 1.8 and 5.1 mT at 10 and 40 GHz, respectively. The damping parameter monotonically decreases as the B2 order of the films increases. This trend is reproduced and explained by ab initio calculations of the electronic structure and damping parameter. Here, the damping parameter is calculated as the structure evolves from A2 to B2 to L2(1) orders. The largest decrease in the damping parameter occurs during the A2 to B2 transition as the half-metallic phase becomes established.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-351424 (URN)10.1103/PhysRevB.97.094420 (DOI)000427798500002 ()
Funder
Swedish Research Council, 2016-04524Swedish Research Council, 2016-06955Swedish Research Council, 2013-08316Knut and Alice Wallenberg Foundation, 2012.0031Knut and Alice Wallenberg Foundation, 2013.0030
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-06-01Bibliographically approved
Keshavarz, S., Kontos, S., Wardecki, D., Kvashnin, Y., Pereiro, M., Panda, S. K., . . . Svedlindh, P. (2018). Magnetic properties of Ruddlesden-Popper phases Sr3-&: A combined experimental and theoretical investigation. Physical Review Materials, 2(4), Article ID 044005.
Open this publication in new window or tab >>Magnetic properties of Ruddlesden-Popper phases Sr3-&: A combined experimental and theoretical investigation
Show others...
2018 (English)In: Physical Review Materials, ISSN 2475-9953, Vol. 2, no 4, article id 044005Article in journal (Refereed) Published
Abstract [en]

We present a comprehensive study of the magnetic properties of Sr3-xYx(Fe1.25Ni0.75)O-7(-delta )(0 <= x <= 0.75). Experimentally, the magnetic properties are investigated using superconducting quantum interference device (SQUID) magnetometry and neutron powder diffraction (NPD). This is complemented by a theoretical study based on density functional theory as well as the Heisenberg exchange parameters. Experimental results show an increase in the Ned temperature (T-N) with an increase of Y concentrations and O occupancy. The NPD data reveal that all samples are antiferromagnetically ordered at low temperatures, which has been confirmed by our theoretical simulations for the selected samples. Our first-principles calculations suggest that the three-dimensional magnetic order is stabilized due to finite interlayer exchange couplings. The latter give rise to finite interlayer spin-spin correlations, which disappear above T-N.

National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-354116 (URN)10.1103/PhysRevMaterials.2.044005 (DOI)000430385300001 ()
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Available from: 2018-06-19 Created: 2018-06-19 Last updated: 2018-08-24Bibliographically approved
Huang, S., Holmstrom, E., Eriksson, O. & Vitos, L. (2018). Mapping the magnetic transition temperatures for medium- and high-entropy alloys. Intermetallics (Barking), 95, 80-84
Open this publication in new window or tab >>Mapping the magnetic transition temperatures for medium- and high-entropy alloys
2018 (English)In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 95, p. 80-84Article in journal (Refereed) Published
Abstract [en]

Tailorable magnetic state near room temperature is very promising for several technological, including magnetocaloric applications. Here using first-principle alloy theory, we determine the Curie temperature (T-C) of a number of equiatomic medium- and high-entropy alloys with solid solution phases. All calculations are performed at the computed lattice parameters, which are in line with the available experimental data. Theory predicts a large crystal structure dependence of T-C, which explains the experimental observations under specified conditions. The sensitivity of the magnetic state to the crystal lattice is reflected by the magnetic exchange interactions entering the Heisenberg Hamiltonian. The analysis of the effect of composition on T-C allows researchers to explore chemistry-dependent trends and design new multi-component alloys with pre-assigned magnetic properties.

Keywords
Curie temperature, High-entropy alloys, First-principle calculations, Monte-Carlo simulations
National Category
Metallurgy and Metallic Materials Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-351640 (URN)10.1016/j.intermet.2018.01.016 (DOI)000428975100010 ()
Funder
Swedish Research CouncilVINNOVA, 2014-03374Swedish Foundation for Strategic Research Carl Tryggers foundation The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Swedish Energy Agency
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2018-06-07Bibliographically approved
Thonig, D., Kvashnin, Y., Eriksson, O. & Pereiro, M. (2018). Nonlocal Gilbert damping tensor within the torque-torque correlation model. Physical review materials, 2(1), Article ID 013801.
Open this publication in new window or tab >>Nonlocal Gilbert damping tensor within the torque-torque correlation model
2018 (English)In: Physical review materials, ISSN 2475-9953, Vol. 2, no 1, article id 013801Article in journal (Refereed) Published
Abstract [en]

An essential property of magnetic devices is the relaxation rate in magnetic switching, which depends strongly on the damping in the magnetization dynamics. It was recently measured that damping depends on the magnetic texture and, consequently, is a nonlocal quantity. The damping enters the Landau-Lifshitz-Gilbert equation as the phenomenological Gilbert damping parameter a, which does not, in a straightforward formulation, account for nonlocality. Efforts were spent recently to obtain Gilbert damping from first principles for magnons of wave vector q. However, to the best of our knowledge, there is no report about real-space nonlocal Gilbert damping aij. Here, a torque-torque correlation model based on a tight-binding approach is applied to the bulk elemental itinerant magnets and it predicts significant off-site Gilbert damping contributions, which could be also negative. Supported by atomistic magnetization dynamics simulations, we reveal the importance of the nonlocal Gilbert damping in atomistic magnetization dynamics. This study gives a deeper understanding of the dynamics of the magnetic moments and dissipation processes in real magnetic materials. Ways of manipulating nonlocal damping are explored, either by temperature, materials doping, or strain.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-341502 (URN)10.1103/PhysRevMaterials.2.013801 (DOI)000419105000001 ()
Available from: 2018-02-13 Created: 2018-02-13 Last updated: 2018-02-13Bibliographically approved
Eriksson, O. (2018). Searching for materials with reduced dimension. Nature Nanotechnology, 13(3), 180-181
Open this publication in new window or tab >>Searching for materials with reduced dimension
2018 (English)In: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 13, no 3, p. 180-181Article in journal, Editorial material (Other academic) Published
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-355828 (URN)10.1038/s41565-017-0060-4 (DOI)000427009000007 ()29402978 (PubMedID)
Available from: 2018-07-06 Created: 2018-07-06 Last updated: 2018-07-27Bibliographically approved
Wang, B.-T., Liu, P.-F., Bo, T., Yin, W., Eriksson, O., Zhao, J. & Wang, F. (2018). Superconductivity in two-dimensional phosphorus carbide (β(o)-PC). Physical Chemistry, Chemical Physics - PCCP, 20(18), 12362-12367
Open this publication in new window or tab >>Superconductivity in two-dimensional phosphorus carbide (β(o)-PC)
Show others...
2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 18, p. 12362-12367Article in journal (Refereed) Published
Abstract [en]

Two-dimensional (2D) boron has been predicted to show superconductivity. However, intrinsic 2D carbon and phosphorus have not been reported to be superconductors, which has inspired us to study the superconductivity of their mixture. Here we performed first-principles calculations for the electronic structure, phonon dispersion, and electron-phonon coupling of the metallic phosphorus carbide monolayer, beta(o)-PC. The results show that it is an intrinsic phonon-mediated superconductor, with an estimated superconducting temperature T-c of similar to 13 K. The main contribution to the electron-phonon coupling is from the out-of-plane vibrations of phosphorus. A Kohn anomaly on the first acoustic branch is observed. The superconducting related physical quantities are found to be tunable by applying strain or by carrier doping.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-356868 (URN)10.1039/c8cp00697k (DOI)000431825300003 ()29700521 (PubMedID)
Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Organisations

Search in DiVA

Show all publications