Derras-Chouk Amel, Chudnovsky Eugene M
Physics Department, Herbert H. Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589, United States of America.
J Phys Condens Matter. 2021 Apr 23;33(19). doi: 10.1088/1361-648X/abe351.
We study the impact of an exchange-reducing defect on a skyrmion in a thin film of finite thickness. Attraction of the skyrmion to a defect is demonstrated in a lattice model by computing the micromagnetic energy accounting for the exchange, Dzyaloshinskii-Moriya interaction, magnetic anisotropy, and dipole-dipole coupling. The spiraling dynamics of the skyrmion toward the defect is illustrated by solving numerically the full Landau-Lifshitz-Gilbert equations on a lattice and, independently, by solving the Thiele equation, with the two methods in agreement with each other. Depinning of the skyrmion by the current is investigated. We find that the skyrmion deforms when it is close to the defect. Deformation is small in the parameter space far from the phase boundary that determines stability of skyrmions. It increases dramatically near the phase boundary, leading to the transformation of the skyrmion by the defect into a snake-like magnetic domain.
我们研究了有限厚度薄膜中一种减少交换的缺陷对斯格明子的影响。通过计算考虑交换、Dzyaloshinskii-Moriya相互作用、磁各向异性和偶极-偶极耦合的微磁能，在晶格模型中证明了斯格明子对缺陷的吸引力。通过在晶格上数值求解完整的朗道-里夫希茨-吉尔伯特方程，并独立地求解蒂勒方程，说明了斯格明子向缺陷的螺旋动力学，两种方法相互一致。研究了电流对斯格明子的脱钉作用。我们发现，斯格明子靠近缺陷时会发生形变。在远离决定斯格明子稳定性的相边界的参数空间中，形变较小。在相边界附近，形变急剧增加，导致缺陷将斯格明子转变为蛇状磁畴。
