TY - JOUR

T1 - Toward room-temperature nanoscale skyrmions in ultrathin films

AU - Varentcova, Anastasiia S.

AU - von Malottki, Stephan

AU - Potkina, Maria N.

AU - Kwiatkowski, Grzegorz

AU - Heinze, Stefan

AU - Bessarab, Pavel F.

N1 - Funding Information: The authors would like to thank V.M. Uzdin, H. Jónsson, S. Blügel, N.S. Kiselev, G.P. Müller, K. von Bergmann, A. Kubetzka, S. Meyer, T. Sigurjónsdóttir for helpful discussions and useful comments. This work was funded by the Russian Science Foundation (Grant no. 17-72-10195), the Icelandic Research Fund (Grants nos. 163048-053, 185409-052, and 184949-052), the University of Iceland Research Fund, the European Union’s Horizon 2020 Research and Innovation Program under Grant agreement no. 665095 (FET-Open project MAGicSky), and the Alexander von Humboldt Foundation. Publisher Copyright: © 2020, The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/12

Y1 - 2020/12

N2 - Breaking the dilemma between small size and room-temperature stability is a necessary prerequisite for skyrmion-based information technology. Here we demonstrate by means of rate theory and an atomistic spin Hamiltonian that the stability of isolated skyrmions in ultrathin ferromagnetic films can be enhanced by the concerted variation of magnetic interactions while keeping the skyrmion size unchanged. We predict film systems where the lifetime of sub-10 nm skyrmions can reach years at ambient conditions. The long lifetime of such small skyrmions is due to exceptionally large Arrhenius pre-exponential factor and the stabilizing effect of the energy barrier is insignificant at room temperature. A dramatic increase in the pre-exponential factor is achieved thanks to the softening of magnon modes of the skyrmion, thereby increasing the entropy of the skyrmion with respect to the transition state for collapse. Increasing the number of skyrmion deformation modes should be a guiding principle for the realization of nanoscale, room-temperature stable skyrmions.

AB - Breaking the dilemma between small size and room-temperature stability is a necessary prerequisite for skyrmion-based information technology. Here we demonstrate by means of rate theory and an atomistic spin Hamiltonian that the stability of isolated skyrmions in ultrathin ferromagnetic films can be enhanced by the concerted variation of magnetic interactions while keeping the skyrmion size unchanged. We predict film systems where the lifetime of sub-10 nm skyrmions can reach years at ambient conditions. The long lifetime of such small skyrmions is due to exceptionally large Arrhenius pre-exponential factor and the stabilizing effect of the energy barrier is insignificant at room temperature. A dramatic increase in the pre-exponential factor is achieved thanks to the softening of magnon modes of the skyrmion, thereby increasing the entropy of the skyrmion with respect to the transition state for collapse. Increasing the number of skyrmion deformation modes should be a guiding principle for the realization of nanoscale, room-temperature stable skyrmions.

UR - http://www.scopus.com/inward/record.url?scp=85097555289&partnerID=8YFLogxK

U2 - 10.1038/s41524-020-00453-w

DO - 10.1038/s41524-020-00453-w

M3 - Article

AN - SCOPUS:85097555289

VL - 6

JO - npj Computational Materials

JF - npj Computational Materials

SN - 2057-3960

IS - 1

M1 - 193

ER -