Skyrmion dynamics and topological sorting on periodic obstacle arrays

Author(s)

Vizarim, N. P. ^{[1, 2, 3]} ; Reichhardt, C. ^{[1, 2]} ; Reichhardt, C. J. O. ^{[1, 2]} ; Venegas, P. A. ^[4]

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, POSMAT Programa Posgrad Ciencia & Tecnol Mat, Fac Ciencias, CP 473, BR-17033360 Bauru, SP - Brazil

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

• Document type: Journal article
• Source: NEW JOURNAL OF PHYSICS; v. 22, n. 5 MAY 2020.
• Web of Science Citations: 0

Abstract

We examine skyrmions under a dc drive interacting with a square array of obstacles for varied obstacle size and damping. When the drive is applied in a fixed direction, we find that the skyrmions are initially guided in the drive direction but also move transverse to the drive due to the Magnus force. The skyrmion Hall angle, which indicates the difference between the skyrmion direction of motion and the drive direction, increases with drive in a series of quantized steps as a result of the locking of the skyrmion motion to specific symmetry directions of the obstacle array. On these steps, the skyrmions collide with an integer number of obstacles to create a periodic motion. The transitions between the different locking steps are associated with jumps or dips in the velocity-force curves. In some regimes, the skyrmion Hall angle is actually higher than the intrinsic skyrmion Hall angle that would appear in the absence of obstacles. In the limit of zero damping, the skyrmion Hall angle is 90 degrees, and we find that it decreases as the damping increases. For multiple interacting skyrmion species in the collective regime, we find jammed behavior at low drives where the different skyrmion species are strongly coupled and move in the same direction. As the drive increases, the species decouple and each can lock to a different symmetry direction of the obstacle lattice, making it possible to perform topological sorting in analogy to the particle sorting methods used to fractionate different species of colloidal particles moving over two-dimensional obstacle arrays. (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