Magnetic Anisotropy in Low-Dimensional System
Abstract: Magnetic anisotropy originated from spin-orbit coupling is the major mechanism to stabilize the magnetism in both ferromagnets and antiferromagnets so that it plays a key role in spintronics for both industrial applications and basic research discoveries. Here, I will introduce our recent studies based on magnetic anisotropy in magnetic thin films. As a special case of uniaxial magnetic anisotropy, perpendicular magnetic anisotropy (PMA) in magnetic thin films meets the requirement for both current and further magnetic storage, such as higher storage density, thermal stability and ultrafast read and write capability. Based on first principles calculations and symmetry analysis, we predicted Giant PMA in Fe/III-V nitride thin films. The magnitude of PMA is up to 50 meV per Fe atom which is over one order larger than any other materials reported. On the other hand, the raising of antiferromagnetic spintronics have greatly advanced the possibility to control magnetism in antiferromagnet (AFM). In an AFM with easy-plane magnetic anisotropy, the Neel vector can be flipped and detected by spin transfer torque and planar Hall effect (PHE) respectively. Our first principles and transport study based on MnTe thin films, a rare example of easy-plane AFM semiconductor, indicates a large zero-field PHE percentage up to 31% which is independent of spin-polarized scattering, and is fundamentally determined by the valence-band anisotropy and spin-momentum locking induced by spin-orbit coupling.