Atomistic spin simulations of electric-field-assisted nucleation and annihilation of magnetic skyrmions in Pd/Fe/Ir(111)Show others and affiliations
2022 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 21, article id 214435Article in journal (Refereed) Published
Abstract [en]
We provide a theoretical background for electric-field-assisted thermally activated writing and deleting of magnetic skyrmions in ultrathin transition-metal films. We apply an atomistic spin model, which includes the exchange interaction, the Dzyaloshinskii-Moriya interaction, and the magnetocrystalline anisotropy energy. The strengths of the magnetic interactions are taken from density functional theory (DFT) calculations for a Pd/Fe bilayer on the Ir(111) surface. We systematically vary all magnetic interactions up to +/- 10% treating the magnetoelectric effect in linear response. The critical magnetic fields marking the onset of the skyrmion phase and the field-polarized phase shift considerably upon varying the interaction constants due to the electric field. Based on harmonic transition state theory, we calculate the transition rates for skyrmion nucleation and annihilation, which are in good agreement with experimental values for Pd/Fe/Ir(111). The field-dependent variation of energy barriers and preexponential factors leads to large changes of the transition rates, which are accompanied by changes in skyrmion radii. Finally, we simulate the electric-field-dependent writing and deleting of magnetic skyrmions in Pd/Fe/Ir(111) based on the master equation and transition rates obtained using the magnetic interactions calculated via DFT for electric fields of epsilon = +/- 0.5 V/angstrom. The magnetic-field-dependent skyrmion probability follows a Fermi-Dirac distribution function of the free energy difference of the skyrmion state and the ferromagnetic (FM) state. The probability function for the opposite electric field directions is in striking agreement with experimental results [Romming et al., Science 341, 636 (2013)].
Place, publisher, year, edition, pages
American Physical Society, 2022. Vol. 105, no 21, article id 214435
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:oru:diva-100335DOI: 10.1103/PhysRevB.105.214435ISI: 000824838900002OAI: oai:DiVA.org:oru-100335DiVA, id: diva2:1684948
Funder
Swedish Research Council, 2020-05110
Note
Funding agencies:
German Research Foundation (DFG) 414321830 (HE3292/11-1)
Icelandic Research Fund 217750 184949
University of Iceland Research Fund 15673
Russian Science Foundation (RSF) 19-72-10138
2022-07-292022-07-292022-11-02Bibliographically approved