硫系超晶格克尔旋转的光子能量依赖性
Photon Energy Dependence of Kerr Rotation in Chalcogenide Superlattices
摘要：
我们报告了基于泵浦-探测的螺旋度相关的时间分辨克尔测量硫属化物超晶格，由交替堆叠的GeTe和Sb $_{2}$ Te $_{3}$层在红外激发下。克尔旋转信号由镜面逆法拉第效应（SIFE）和镜面光学克尔效应（SOKE）组成，这两者都被发现在亚电子伏特的能量范围内随着光子能量的降低而单调增加。虽然SIFE的依赖性可以归因于直接三阶非线性极化率的响应函数，但SOKE的大小反映了从体价带到超晶格的界面起源狄拉克态的电子跃迁所产生的级联二阶非线性极化率。
英文摘要：
We report on pump-probe based helicity dependent time-resolved Kerr measurements of chalcogenide superlattices, consisting of alternately stacked GeTe and Sb$_{2}$Te$_{3}$ layers under infrared excitation. The Kerr rotation signal consists of the specular Inverse Faraday effect (SIFE) and the specular optical Kerr effect (SOKE), both of which are found to monotonically increase with decreasing photon energy over a sub-eV energy range. Although the dependence of the SIFE can be attributed to a response function of direct third-order nonlinear susceptibility, the magnitude of the SOKE reflects cascading second-order nonlinear susceptibility resulting from electronic transitions from bulk valence band to interface-originating Dirac states of the superlattice.
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