Magnetic Switching by Spin Hall Effect: a Comparison Between Simulations and Experimental Observations

• Main Authors: CHUNG,CHENG-TING, 鍾政廷
• Other Authors: CHERN,GUNG
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/q4x5y7

碩士 === 國立中正大學 === 物理學系暨研究所 === 103 === In this thesis, we study magnetization switching by spin Hall effect (SHE), which is induced by in-plane injected currents in the Ta/CoFeB/MgO system with perpendicularly anisotropic. We use the Landau–Lifshitz–Gilbert(LLG) equation to simulate the time evolution of magnetization and compare the result with experimental observations. The simulated results are divided into 4 parts: 1. Simulations of the magnetic switching by varying injected currents with a fixed in-plane magnetic field and predictions for current-induced magnetic switching with the LLG equation. The critical current density of magnetic switching (Jc) is calculated by analytic methods with the condition of variance of Jc with respect to various angles of the applied magnetic field. 2. Simulations of varying applied magnetic field with a fixed injected current We simulate the dependence of hysteresis loops upon positive (negative) current density with different values. We obtain the coercivity (Hc) by analytic methods and its dependence on the angle of applied magnetic field. 3. A comparison between simulations and experimental data in Ta(5)/Co4Fe4B2(1.1)/MgO(1)/Ta(5) structure (unit: nm). The comparison has led us to obtain the effective field induced by SHE and phase diagrams of Jc and Hc. These results were also used to analyze the behaviors of changing the angle of applied magnetic field. 4. Possibility of current induced magnetic switching without applied external magnetic field By introducing a tilted uniaxial perpendicular magnetic anisotropy, we are able to simulate of the magnetic switching without external field. From these results we learned physics behind the breaking of the intrinsic symmetry in the SHE induced magnetic switching in perpendicular magnetized thin film structures.