多铁半导体(Ge,Mn)Te中的激光诱导Rashba自旋轨道矩
Laser-Induced Rashba Spin-Orbit Torques in Multiferroic Semiconductor (Ge,Mn)Te
AI总结：
本研究针对多铁半导体(Ge,Mn)Te，利用时间分辨磁光光谱发现两种激光诱导的自旋轨道矩，其中第二种为该材料特有，为自旋电子器件的磁有序全光操控提供了新途径。
AI中文摘要：
多铁半导体GeMnTe兼具铁电性、强Rashba自旋轨道耦合以及载流子介导的磁有序，是探究电子、结构与磁自由度间相互作用的独特平台。本研究采用时间分辨磁光光谱研究Ge₀.₈₅Mn₀.₁₅Te的超快磁化动力学，通过分离瞬态响应中的磁性与非磁性贡献，识别出两种不同的激光诱导磁现象，二者均源于光致有效自旋轨道矩。相干磁化进动由激光诱导空穴浓度增加引发，该变化会改变Rashba分裂的自旋锁定价带态的占据情况，进而调整磁易轴；而观测到的矫顽力变化所体现的磁有序瞬态改变，则归因于激光诱导的铁电亚晶格位移修改，这一变化会影响铁电极化及相关的Rashba自旋轨道相互作用。第一种光自旋轨道矩已在稀释磁性半导体(Ga,Mn)As中观测到，第二种效应则是多铁Rashba半导体(Ge,Mn)Te所特有的，为自旋电子器件中磁有序与自旋轨道矩产生的全光操控开辟了新机遇。
英文摘要：
The multiferroic semiconductor GeMnTe exhibits ferroelectricity, strong Rashba spin-orbit coupling, and carrier-mediated magnetic order, making it a unique platform for exploring the interplay among electronic, structural, and magnetic degrees of freedom. In this study, we investigate the ultrafast magnetization dynamics of Ge0.85Mn0.15Te using time-resolved magneto-optical spectroscopy. By separating magnetic and nonmagnetic contributions in the transient response, we identify two distinct laser-induced magnetic phenomena, both resulting from photoinduced effective spin-orbit torque. Coherent magnetization precession arises from a laser-induced increase in hole concentration, which modifies the occupation of Rashba-split spin-locked valence band states and alters the magnetic easy axis. The transient change in magnetic ordering, observed as variations in the coercive field, is attributed to laser-induced modifications of the ferroelectric sublattice displacement, which affect the ferroelectric polarization and the associated Rashba spin-orbit interaction. While the first type of optical spin-orbit torque has already been observed in the diluted magnetic semiconductor (Ga,Mn)As, the second effect is unique to the multiferroic Rashba semiconductor (Ge,Mn)Te, opening new opportunities for all-optical manipulation of magnetic order and spin-orbit torque generation in spin-orbitronic devices.
