Mijatović Svetislav, Branković Milica, Graovac Stefan, Spasojević Djordje
Faculty of Physics, University of Belgrade, P. O. Box 44, 11001 Belgrade, Serbia.
Phys Rev E. 2020 Aug;102(2-1):022124. doi: 10.1103/PhysRevE.102.022124.
We present numerical findings on the behavior of the athermal nonequilibrium random-field Ising model of spins at the thin striplike L_{1}×L_{2}×L_{3} cubic lattices with L_{1}<L_{2}<L_{3}. Changing of system sizes highly influences the evolution and shape of avalanches. The smallest avalanches [classified as three-dimension- (3D) like] are unaffected by the system boundaries, the larger are sandwiched between the top and bottom system faces so are 2D-like, while the largest are extended over the system lateral cross section and propagate along the length L_{3} like in 1D systems. Such a structure of avalanches causes double power-law distributions of their size, duration, and energy with larger effective critical exponent corresponding to 3D-like and smaller to 2D-like avalanches. The distributions scale with thickness L_{1} and are collapsible following the proposed scaling predictions which, together with the distributions' shape, might be important for analysis of the Barkhausen noise experimental data for striplike samples. Finally, the impact of system size on external field that triggers the largest avalanche for a given disorder is presented and discussed.
我们展示了关于自旋的无热非平衡随机场伊辛模型在具有(L_{1}<L_{2}<L_{3})的薄带状(L_{1}×L_{2}×L_{3})立方晶格上行为的数值研究结果。系统尺寸的变化对雪崩的演化和形状有很大影响。最小的雪崩（归类为类似三维（3D）的）不受系统边界影响，较大的雪崩夹在系统的顶面和底面之间，因此类似二维，而最大的雪崩在系统横向横截面扩展并沿长度(L_{3})传播，如同在一维系统中一样。这种雪崩结构导致其大小、持续时间和能量呈现双幂律分布，对应类似3D雪崩的有效临界指数较大，而对应类似二维雪崩的较小。这些分布随厚度(L_{1})缩放，并且根据所提出的缩放预测是可压缩的，这与分布的形状一起，可能对带状样品的巴克豪森噪声实验数据分析很重要。最后，给出并讨论了系统尺寸对触发给定无序状态下最大雪崩的外场的影响。
