Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Phys Rev E. 2019 Oct;100(4-1):042121. doi: 10.1103/PhysRevE.100.042121.
Simulations with more than 10^{12} spins are used to study the motion of a domain wall driven through a three-dimensional random-field Ising magnet (RFIM) by an external field H. The interface advances in a series of avalanches whose size diverges at a critical external field H_{c}. Finite-size scaling is applied to determine critical exponents and test scaling relations. Growth is intrinsically anisotropic with the height of an avalanche normal to the interface ℓ_{⊥} scaling as the width along the interface ℓ_{∥} to a power χ=0.85±0.01. The total interface roughness is consistent with self-affine scaling with a roughness exponent ζ≈χ that is much larger than values found previously for the RFIM and related models that explicitly break orientational symmetry by requiring the interface to be single-valued. Because the RFIM maintains orientational symmetry, the interface develops overhangs that may surround unfavorable regions to create uninvaded bubbles. Overhangs complicate measures of the roughness exponent but decrease in importance with increasing system size.
使用超过 10^{12} 个自旋的模拟来研究通过外部场 H 驱动穿过三维随机场伊辛磁体 (RFIM) 的畴壁的运动。界面在一系列大小发散的雪崩中前进，在临界外部场 H_{c} 处。应用有限尺寸标度来确定临界指数并检验标度关系。增长具有固有各向异性，与界面垂直的雪崩高度 ℓ_{⊥} 沿界面 ℓ_{∥} 以幂 χ=0.85±0.01 缩放。总界面粗糙度与自相似标度一致，粗糙度指数 ζ≈χ 远大于以前在 RFIM 和相关模型中发现的值，这些模型通过要求界面为单值来明确打破方向对称性。由于 RFIM 保持方向对称性，界面会形成悬垂部分，这些悬垂部分可能会包围不利区域，以创建未入侵的气泡。悬垂部分会使粗糙度指数的测量变得复杂，但随着系统尺寸的增加，其重要性会降低。
