随着半导体工艺的飞速发展，存储器件尺寸微缩即将达到物理极限，摩尔定律即将失效，迫切需要发展新型存储技术。SOT-MRAM由于其低功耗、高密度、非易失性等优势而成为极具潜力的候选存储技术。对SOT的研究是发展低功耗SOT-MRAM存储技术的关键。单晶外延的薄膜具有清晰的晶体结构以及能够实现高质量界面的磁性异质结，有利于探索材料中SOT产生和增强的物理机制。本论文围绕外延生长的单晶Pt/Co和LSMO/Pt两种磁性异质结，对两种体系的SOT效应展开研究，主要内容包括：
（1）利用分子束外延（MBE）制备了不同厚度Pt/Co(t nm)多层膜体系，研究了其磁学特性。通过二次谐波霍尔电压测试表征了Pt/Co样品中的SOT，并分离出体系中的类阻尼力矩效率和类场力矩效率，得到体系的SOT效率为0.052。此外，利用MOKE观察了外延Pt/Co体系在面内场辅助下实现完全磁化翻转的过程，磁畴从中心形核及磁畴壁向外扩张。这项工作有助于对单晶外延磁性异质结中SOT磁化翻转过程的理解，为发展SOT-MRAM提供了合适的候选体系。
（2）利用激光脉冲沉积和磁控溅射在STO(001)衬底上制备了La0.67Sr0.33MnO3(001)(LSMO)/Pt磁性异质结，并对其晶体结构、形貌以及磁学特性进行了表征。通过铁磁共振（FMR）和自旋力矩铁磁共振（ST-FMR）高频测试技术对该磁异质结的磁化动力学行为展开研究，得到体系中~10-3数量级的低磁阻尼系数以及高达0.15的SOT效率。这项研究工作表明了铁磁氧化物材料LSMO与传统金属Pt相结合能够有效提高传统金属Pt体系的SOT效率，为开发高性能SOT器件提供了一种理想的候选材料体系。

With the rapid development of semiconductor technology, the miniaturization of storage devices is approaching its physical limits, and Moore's Law is on the verge of becoming ineffective. There is an urgent need to develop new storage technologies. Spin-orbit torque magnetic random-access memory (SOT-MRAM) has emerged as a highly promising candidate due to its advantages such as low power consumption, high density, and non-volatility. The study of spin-orbit torque (SOT) is key to the development of low-power SOT-MRAM storage technology. Epitaxial thin films with well-defined crystal structures and the ability to achieve high-quality interfaces play a crucial role in exploring the physical mechanisms underlying SOT generation and enhancement in materials. This paper focuses on the investigation of SOT effects in two magnetic heterostructures: single-crystal epitaxial Pt/Co and LSMO/Pt. The main contents include:
(1) Multiple layers of Pt/Co (t nm) were prepared using molecular beam epitaxy (MBE), and their magnetic properties were studied. Second harmonic Hall voltage measurements were used to characterize the SOT in the Pt/Co samples, separating the contributions from damping-like and field-like torques. The SOT efficiency of the system was determined to be 0.052. Additionally, magneto-optic Kerr effect (MOKE) was employed to observe the complete magnetization reversal process in the epitaxial Pt/Co system assisted by an in-plane field. Magnetic domains nucleated at the center and expanded outwardly. This work contributes to the understanding of the magnetization reversal process driven by SOT in single-crystal epitaxial magnetic heterostructures, providing suitable candidate systems for the development of SOT-MRAM.
(2) La0.67Sr0.33MnO3(001)(LSMO)/Pt magnetic heterostructures were prepared on STO(001) substrates using Pulsed Laser Deposition and Magnetron Sputtering techniques. The crystal structure, morphology, and magnetic properties of the heterostructure were characterized. The magnetization dynamics of the system were studied through ferromagnetic resonance (FMR) and spin-torque ferromagnetic resonance (ST-FMR) techniques. The results showed a low damping coefficient on the order of 10-3 and an SOT efficiency as high as 0.15 in the system. This research demonstrates that combining the ferromagnetic oxide material LSMO with traditional metal Pt can effectively enhance the SOT efficiency in conventional Pt systems, providing an ideal candidate material system for developing high-performance SOT devices.