Skyrmion dynamics and transverse mobility: skyrmion Hall angle reversal on 2D periodic substrates with dc and biharmonic ac drives

Author(s)

Vizarim, Nicolas P. ^{[1, 2, 3]} ; Reichhardt, Cynthia J. O. ^{[1, 2]} ; Venegas, Pablo A. ^[4] ; Reichhardt, Charles ^{[1, 2]}

Affiliation

^[1] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 - USA

^[2] Los Alamos Natl Lab, Ctr Nonlinear Studies, Los Alamos, NM 87545 - USA

^[3] Univ Estadual Paulista UNESP, Fac Ciencias, POSMAT Programa Posgrad Ciencia & Tecnol Mat, BR-17033360 Bauru, SP - Brazil

^[4] Univ Estadual Paulista UNESP, Fac Ciencias, Dept Fis, CP 473, BR-17033360 Bauru, SP - Brazil

• Document type: Journal article
• Source: European Physical Journal B; v. 93, n. 6 JUN 17 2020.
• Web of Science Citations: 0

Abstract

We numerically examine the dynamics of a skyrmion interacting with a two-dimensional periodic substrate under dc and biharmonic ac drives. We show that the Magnus force of the skyrmion produces circular orbits that can resonate with the ac drive and the periodicity of the substrate to create quantized motion both parallel and perpendicular to the dc drive. The skyrmion Hall angle exhibits a series of increasing and/or decreasing steps along with strongly fluctuating regimes. In the phase locked regimes, the skyrmion Hall angle is constant and the skyrmion motion consists of periodic orbits encircling an integer number of obstacles per every or every other ac drive cycle. We also observe phases in which the skyrmion moves at 90 degrees with respect to the driving direction even in the presence of damping, a phenomenon called absolute transverse mobility that can exhibit reentrance as a function of dc drive. When the biharmonic ac drives have different amplitudes in the two directions, we find regimes in which the skyrmion Hall angle shows a sign reversal from positive to negative, as well as a reentrant pinning effect in which the skyrmion is mobile at low drives but becomes pinned at higher drives. These behaviors arise due to the combination of the Magnus force with the periodic motion of the skyrmions, which produce Shapiro steps, directional locking, and ratchet effects. (AU)

• FAPESP's process: 18/13198-7 - Dynamic behavior of skyrmions under the influence of periodic pinning in chiral magnetic infinite thin films
• Grantee: Nicolas Porto Vizarim
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate