Lan Shoufeng, Liu Xiaoze, Wang Siqi, Zhu Hanyu, Liu Yawen, Gong Cheng, Yang Sui, Shi Jing, Wang Yuan, Zhang Xiang
Nanoscale Science and Engineering Center, University of California, Berkeley, CA, USA.
Department of Mechanical Engineering, Texas A&M University, College Station, TX, USA.
Nat Commun. 2021 Apr 7;12(1):2088. doi: 10.1038/s41467-021-22412-9.
The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.
手性与磁性之间的相互作用产生了一种独特的物理过程——磁手性效应，这使得人们能够开发出仅靠两者中的任何一个都无法实现的功能。这种过程在同时打破宇称反转和时间反演对称性时具有普遍性。然而，迄今为止观察到的磁手性效应在物质对光子、电子或声子作出响应时很微弱。在此，我们报告了在扭曲双层二硫化钨中首次观察到对激子的强磁手性响应，其激子磁手性（ExMCh）各向异性的幅度达到约4%的值。我们进一步发现ExMCh各向异性具有约7纳米的光谱分裂特征，恰好是激子手性光谱的半高全宽。在没有外部施加强磁场的情况下，在室温下从铥铁石榴石的铁磁衬底观察到的具有自发磁矩的ExMCh效应有利于器件应用。独特的ExMCh过程为在光化学反应、不对称合成和药物递送中主动控制磁手性应用提供了一条新途径。
