Anisotropic critical behavior of current-driven skyrmion dynamics in chiral magnets with disorder

• Published in: New journal of physics Vol. 22; no. 3; pp. 33043 - 33052
• Main Authors: Xiong, L, Zheng, B, Jin, M H, Zhou, N J
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2020
• Subjects: Adiabatic flow; Computer simulation; Critical current (superconductivity); critical dynamics; depinning phase transition; Exponents; Hall effect; Hypothetical particles; Landau-Lifshitz-Gilbert equation; Magnetic materials; Magnets; Particle theory; Phase transitions; Physics; Robustness (mathematics); skyrmions; Spin dynamics; Threshold currents; Torque
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/ab74ab

The dynamic pinning effects are significant in manipulating skymions in chiral magnetic materials with quenched disorder. Through numerical simulations of the non-stationary current-driven dynamics of skyrmions with the Landau-Lifshitz-Gilbert equation, the critical current, static and dynamic critical exponents of the depenning phase transition are accurately determined for both adiabatic and non-adiabatic spin-transfer torques and with different strengths of disorder, based on the dynamic scaling behavior far from stationary. We find that the threshold current is insensitive to a small non-adiabatic coefficient of the spin-transfer torque, but dramatically reduced for a large one. The critical exponents indicate that the critical dynamic behavior is robust for different spin-transfer torques in the perpendicular component of the Hall motion, while exhibits a weak universality class in the direction of the driving current. The anisotropic behavior around the depinning phase transition provides a quantitative analysis of the drive-dependent skyrmion Hall effect in experiments. Further, the theoretical analysis using the Thiele's approach is presented, and the critical current and the static exponents support the simulation results.