摘要
磁光克尔效应是指处于磁场中的光束在磁体表面发生反射时,反射光的偏振面相对入射光发生旋转的物理现象,它反映了磁化强度对磁性材料光学性质的影响.磁性介质的磁光克尔效应则由含磁光常数的介电张量表征,因此对磁光常数进行精确测量具有重要的科学意义.光子自旋霍尔效应表现为光束在折射率不同的介质界面上传输时由于自旋-轨道相互作用而产生的光子自旋分裂现象.过去大多数研究利用光子自旋霍尔效应的横向空间位移来表征磁光常数.然而,现有工作只考虑了单个磁场方向的磁光克尔效应,并且由于微小的自旋空间位移而需要引入复杂的弱测量技术.本文从理论上全面探究了3种磁光克尔效应条件下的面内自旋角位移,发现通过改变磁场方向和磁性材料的厚度(考虑块状和超薄)可以实现对光子自旋霍尔效应的有效操纵.同时,该研究提出了一种直接测量磁光常数的新方法,即通过直接观测巨大的面内自旋角位移来表征磁光常数的振幅与相位.该方法不需要引入弱测量系统,不仅为磁光常数的测量提供了直接有效的探针,并且扩展了自旋光子学的相关研究.
The magneto-optical Kerr effect(MOKE)refers to the rotation of the polarization plane when a linearly polarized light is reflected at the surface of magnetic material.The MOKE reveals the magnetization of the optical properties of magnetic material and can be characterized by the dielectric tensor containing the magneto-optical constant.Thus,exploring the MOKE requires very precise determination of the magnetooptical constant.The photonic spin Hall effect(PSHE),which corresponds to the lateral and in-plane spindependent splitting of the beam,can be used as an effective method to characterize the magneto-optical constant due to its advantage of being extremely sensitive to changes in the physical parameters of the material.Most of the previous studies only considered the case of a single thickness of magnetic material and a single MOKE and need to introduce complex weak measurement techniques to observe the photonic spin Hall effect.In this work,we theoretically investigate the in-plane spin angular shifts in three MOKE cases in bulk and ultrathin magnetic materials.We can effectively tune the in-plane angular displacements of different magnetic material thickness by changing the magnetic field direction corresponding to different MOKEs and changing the magneto-optical constants(including amplitude and phase).The research results show that in the case of bulk and ultrathin magnetic materials,the internal spin angular displacements under different MOKEs will show different trends when the magneto-optical constants change the amplitude and phase,especially in ultra-thin magnetic material.In the lateral Kerr effect in thin material,the photon in-plane angular displacement does not affect the change of the magneto-optical constant,but in other cases,the amplitude relative to the phase has a much larger effect on the photon in-plane angular displacement.In this regard,we propose a new method which can directly determine the amplitude and phase of the magneto-optical constant by using the huge in-plane spin angular displacement without considering the weak measurements and can also judge different MOKEs according to the variation of the in-plane angular displacement in the bulk and ultrathin magnetic materials.This method not only provides a new probe for measuring magneto-optical constants but also expands the study of spin photonics.
作者
李乾阳
袁帅杰
杨锦
王勇
马祖海
陈宇
周新星
Li Qian-Yang;Yuan Shuai-Jie;Yang Jin;Wang Yong;Ma Zu-Hai;Chen Yu;Zhou Xin-Xing(Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education,Synergetic Innovation Center for Quantum Effects and Applications,School of Physics and Electronics,Hunan Normal University,Changsha 410081,China;International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology,Institute of Microscale Optoelectronics,Shenzhen University,Shenzhen 510086,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第1期105-114,共10页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11604095)
湖南省自然科学基金(批准号:2017JJ3209)
长沙市杰出创新青年培养计划(批准号:KQ2107013)资助的课题。
