Shin Dongbin, Hübener Hannes, De Giovannini Umberto, Jin Hosub, Rubio Angel, Park Noejung
Department of Physics, Ulsan National Institute of Science and Technology, UNIST-gil 50, Ulsan, 44919, Korea.
Max Planck Institute for the Structure and Dynamics of Matter, Center for Free-Electron Laser Science, Luruper Chaussee 149, Hamburg, 22761, Germany.
Nat Commun. 2018 Feb 12;9(1):638. doi: 10.1038/s41467-018-02918-5.
Two-dimensional materials equipped with strong spin-orbit coupling can display novel electronic, spintronic, and topological properties originating from the breaking of time or inversion symmetry. A lot of interest has focused on the valley degrees of freedom that can be used to encode binary information. By performing ab initio time-dependent density functional simulation on MoS, here we show that the spin is not only locked to the valley momenta but strongly coupled to the optical E″ phonon that lifts the lattice mirror symmetry. Once the phonon is pumped so as to break time-reversal symmetry, the resulting Floquet spectra of the phonon-dressed spins carry a net out-of-plane magnetization (≈0.024μ for single-phonon quantum) even though the original system is non-magnetic. This dichroic magnetic response of the valley states is general for all 2H semiconducting transition-metal dichalcogenides and can be probed and controlled by infrared coherent laser excitation.
具有强自旋轨道耦合的二维材料可展现出源于时间或空间反演对称性破缺的新颖电子、自旋电子及拓扑性质。诸多研究兴趣聚焦于可用于编码二进制信息的能谷自由度。通过对二硫化钼进行从头算含时密度泛函模拟，我们在此表明，自旋不仅锁定于能谷动量，还与打破晶格镜面对称性的光学E″声子强烈耦合。一旦泵浦声子以打破时间反演对称性，即便原始系统是非磁性的，声子修饰自旋的所得弗洛凯光谱也会携带净面外磁化强度（单声子量子约为0.024μ）。能谷态的这种二向色性磁响应对于所有2H型半导体过渡金属二硫属化物而言都是普遍存在的，并且可以通过红外相干激光激发进行探测和控制。
