Belim Sergey V, Bychkov Igor V
Department of Physics, Omsk State Technical University, 644050 Omsk, Russia.
Department of Radiophysics and Electronics, Chelyabinsk State University, 454001 Chelyabinsk, Russia.
Materials (Basel). 2023 Oct 17;16(20):6728. doi: 10.3390/ma16206728.
This article performs computer simulations of the change in magnetization in the ferromagnetic film when polarized electric current passes through it. The model examines multilayer structures from ferromagnetic and nonmagnetic films. A sandwich system comprises two ferromagnetic layers separated by a nonmagnetic gasket. Ferromagnetic films have different magnetic susceptibility. The first ferromagnetic film is magnetically hard and acts as a fixed layer. The second ferromagnetic film is magnetically soft, with a switched direction of magnetization. The current direction is perpendicular to the film plane (CPP geometry). Spin transfer is carried out by electrons that polarize in the first ferromagnetic film and transmit spin to the second ferromagnetic film. We use the Ising model to describe the magnetic properties of the system and the Metropolis algorithm to form the thermodynamic states of the spin system. Simulations are performed at temperatures below the Curie points for both materials. The result of computer simulation is the dependence of magnetization in the magnetically soft film on the current strength in the system. Calculations show that there is a critical value of the current at which the magnetization sign of the controlled film changes. The magnetization versus current plot is stepwise. The change in the magnetization sign is due to an increase in the polarization of the electron gas. The plot of electron gas polarization versus current is also stepwise.
本文对极化电流通过铁磁薄膜时其磁化强度的变化进行了计算机模拟。该模型研究了由铁磁薄膜和非磁薄膜组成的多层结构。一个三明治系统由两层被非磁垫片隔开的铁磁层组成。铁磁薄膜具有不同的磁化率。第一个铁磁薄膜是硬磁的，充当固定层。第二个铁磁薄膜是软磁的，其磁化方向会发生切换。电流方向垂直于薄膜平面（电流垂直平面几何结构）。自旋转移是由在第一个铁磁薄膜中极化并将自旋传递到第二个铁磁薄膜的电子来实现的。我们使用伊辛模型来描述系统的磁特性，并使用 metropolis 算法来形成自旋系统的热力学状态。在两种材料的居里温度以下进行模拟。计算机模拟的结果是软磁薄膜中的磁化强度与系统中电流强度的关系。计算表明，存在一个电流临界值，在该临界值时被控制薄膜的磁化方向会发生改变。磁化强度与电流的关系曲线是阶梯状的。磁化方向的改变是由于电子气极化的增加。电子气极化与电流的关系曲线也是阶梯状的。
