He Junjie, Li Shuo, Frauenheim Thomas, Zhou Zhaobo
Faculty of Science, Department of Physical and Macromolecular Chemistry, Charles University, Prague 12843, Czech Republic.
Institute of Advanced Study, Chengdu University, Chengdu 610100, China.
Nano Lett. 2023 Sep 13;23(17):8348-8354. doi: 10.1021/acs.nanolett.3c02727. Epub 2023 Aug 29.
We employ real-time time-dependent density functional theory (rt-TDDFT) and ab initio nonadiabatic molecular dynamics (NAMD) to systematically investigate the ultrafast laser pulses induced spin transfer and relaxation dynamics of two-dimensional (2D) antiferromagnetic-ferromagnetic (AFM/FM) MnPS/MnSe van der Waals heterostructures. We demonstrate that laser pulses can induce a ferrimagnetic (FiM) state in the AFM MnPS layer within tens of femtoseconds and maintain it for subpicosecond time scale before reverting to the AFM state. We identify the mechanism in which the asymmetric optical intersite spin transfer (OISTR) effect occurring within the sublattices of the AFM and FM layers drives the interlayer spin-selective charge transfer, leading to the transition from AFM to FiM state. Furthermore, the unequal electron-phonon coupling of spin-up and spin-down channels of AFM spin sublattice causes an inequivalent spin relaxation, in turn extending the time scale of the FiM state. These findings are essential for designing novel optical-driven ultrafast 2D magnetic switches.
我们采用实时含时密度泛函理论（rt-TDDFT）和从头算非绝热分子动力学（NAMD），系统地研究了超快激光脉冲诱导的二维（2D）反铁磁-铁磁（AFM/FM）MnPS/MnSe范德华异质结构中的自旋转移和弛豫动力学。我们证明，激光脉冲可在几十飞秒内在AFM MnPS层中诱导出亚铁磁（FiM）态，并在恢复到AFM态之前的亚皮秒时间尺度内保持该状态。我们确定了一种机制，即AFM和FM层亚晶格内发生的不对称光学位点间自旋转移（OISTR）效应驱动层间自旋选择性电荷转移，导致从AFM态转变为FiM态。此外，AFM自旋亚晶格的自旋向上和自旋向下通道的不等电子-声子耦合导致不等价的自旋弛豫，进而延长了FiM态的时间尺度。这些发现对于设计新型光驱动超快二维磁开关至关重要。
