Reversible vector ratchets for skyrmion systems

Journal Article · 03 March 2017 · Physical Review B

DOI: https://doi.org/10.1103/PhysRevB.95.104401 · OSTI ID:1356134

Ma, Xiu ^[1]; Reichhardt, Cynthia Jane Olson  ^[2]; Reichhardt, Charles ^[2]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Univ. of Notre Dame, IN (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

In this paper, we show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360° rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is always parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Finally, since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: AC52-06NA25396; 89233218CNA000001
• OSTI ID: 1356134
• Alternate ID(s): OSTI ID: 1345685; OSTI ID: 1768526
• Report Number(s): LA-UR-16-27322; LA-UR-18-30669; TRN: US1702609
• Journal Information: Physical Review B, Vol. 95, Issue 10; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English