| Time：1120426 (Wed.) 14:20~16:20 Speaker：Prof.唐毓慧(Yu-Hui Tang) 國立中央大學物理學系/Department of physics, National Central University Title：Determination of magnetic anisotropy in magnetic heterostructures: DFT-based spin torque method. Abstract： In order to increase the storage capacity of magnetoresistive random-access memories (MRAMs), the reduction of size of memory cell requires the enhancement of the magnetic anisotropy to meet the criterion of thermal stability. The recently discovered perpendicular magnetic anisotropy (PMA) at the ferromagnetic metal/oxide and ferromagnetic metal/heavy metal interfaces plays a crucial role in MRAM applications. However, both first-principles calculated total energy and fitted experimental data remain difficult to quantitatively evaluate the magnetic anisotropy energy (MAE), especially in magnetic heterostructures with complex interfaces between multi-layers. An alternative solution is the so-called spin-orbit torque (SOT) method. In this study, the validity of our DFT-based self-developed JunPy package with SOT calculation has been rigorously confirmed in three kinds of PMA systems, including iron thin films, Fe/MgO/Fe magnetic tunnel junction, and Co/Pd magnetic bilayer. Our results agree with the conventional MAE calculation but provide deeper insights into atomistic spin dynamics of local magnetic moments. The main advantage of this DFT+JunPy+SOT method is to provide the well-decomposed layer-resolved SOT and SOC-dominated spin current accumulation and the comprehensive physical understanding in angular momentum transfer between spin and orbital, competition between SOT and spin current accumulation, and precise spin torque acting on each local magnetic moment that is crucial for the atomistic spin dynamics especially in magnetic heterostructures. Place：S101, Gongguan Campus, NTNU |
