在磁阻式隨機存取記憶體 (magnetoresistive random-access memory，MRAM) 中，自由層材料的磁性特性：磁異向性 (magnetic anisotropy，Ku)、飽和磁矩 (saturation magnetization，Ms)，對於評估記憶體的操作至關重要。然而在傳統的理論計算或實驗方法中，往往只能透過等效參數來估算複合材料的磁性特性，鮮少能獨立區分出個別原子的貢獻，這阻礙了對異質材料進行更深層的分析。 因此在過去我們開發了「JunPy」程式，提供了一種進行原子級解析 (atomic-resolved) 材料磁性結構的方法，並透過多種方法驗證此程式的有效性。然而僅進行了原子級磁性特性的解析，仍不足以充分了解異質結構在受到外部刺激時的響應。因此我們整合了密度泛函理論 (density functional theory，DFT)、自旋軌道力矩 (spin-orbit torque，SOT) 和朗道-利夫希茲-吉爾伯特方程式 (Landau–Lifshitz–Gilbert simulation，LLG) 的模擬，提出了 「DFT-SOT-LLG Simulation (DSLS) 」模擬計算流程。此流程無須任何經驗模型或參數擬合，即可產出能與實驗相對照的模擬結果。 在這篇論文中，我們透過兩個系統來演示 DSLS 的計算流程：(1) 1/3 Cr 插層的 CeTe2；(2) 極薄與塊材 Cr2Te3。在第一個系統中，我們成功計算出了整體系統的面內磁異向性 (in-plane magnetic anisotropy，IMA) 是由表面的 IMA 與中心的垂直磁異向性 (perpendicular magnetic anisotropy、PMA) 共同決定，並揭示了 Te 在 Cr-Te 化合物中的重要性，最終透過 LLG 模擬演示了這兩種磁異向性組合在外加磁場下的行為。在第二個系統中，我們使用 DSLS 模擬出與實驗相符的磁滯曲線 (hysteresis loop)，並進一步揭示了實驗中量測到的特殊兩階段磁滯曲線來源，充分演示了 DSLS 計算流程在實際應用上的可行性。;In magnetoresistive random-access memory (MRAM)， understanding the magnetic properties of the free layer， such as magnetic anisotropy (Ku) and saturation magnetization (Ms)， is crucial for evaluating memory operation. However， traditional theoretical calculations and experimental methods often rely on effective magnetic anisotropy (MA). They rarely distinguish individual atomic contributions， which hinders deeper analysis of heterostructures. To address this， we previously developed "JunPy，" a program that provides a method for atomic-resolved analysis of MA， with its validity verified through various approaches. Nevertheless， atomic-resolved analysis alone is insufficient to fully understand how heterostructures respond to external stimuli. Therefore， we integrated Density Functional Theory (DFT)， Spin-Orbit Torque (SOT)， and Landau–Lifshitz–Gilbert (LLG) simulations to propose the "DFT-SOT-LLG Simulation (DSLS)" workflow. This workflow produces simulation results comparable to experimental data without the need for empirical models or parameter fitting. In this thesis， we demonstrate the DSLS workflow using two systems: (1) Cr1/3-intercalated CrTe2; and (2) ultrathin and bulk Cr2Te3. In the first system， we successfully calculated that the overall in-plane magnetic anisotropy (IMA) is co-determined by surface IMA and bulk perpendicular magnetic anisotropy (PMA). We also revealed the significance of Te in Cr-Te compounds and used LLG simulations to demonstrate the behavior of these combined anisotropies under an external magnetic field. In the second system， we employed DSLS to simulate hysteresis loops that match experimental results and further identified the origin of the unique two-stage hysteresis loops observed in experiments. These results fully demonstrate the feasibility of the DSLS workflow in practical applications.
