论文标题
几层NBSE2的非线性光学厅效应
Nonlinear optical Hall effect of few-layered NbSe2
论文作者
论文摘要
nbse $ _2 $是金属二维（2D）过渡金属二核化（TMDC）材料之一。由于晶体反转的对称性破裂，大型旋转分裂是通过在奇数数量的nbse $ _2 $中诱导的型自旋轨道耦合，但与反转对称的偶数数量的nbse $ _2 $不存在。在本文中，我们根据有效的紧密结合模型计算了几层NBSE $ _2 $的非线性光电电荷和旋转大厅的电导率，其中包括$ d_ {z^2} $，$ d_ {x^2-y^2} $和$ d_ {xy} $ d_ {xy} $ orbit nb Atom Atom Atom的$ orbitals。我们表明，第二次谐波生成（SHG）过程的非线性光学厅电导率在奇数式的NBSE $ _2 $中具有非变化值。另外，我们以几层NBSE $ _2 $及其两极化依赖性提供非线性光学选择规则。另外，对于偶数层的情况，可以通过施加破坏反转对称性的电场来产生非线性光学厅电流。我们还讨论了通常在TMDC材料中发生非线性光学霍尔效应。因此，我们的结果将有助于基于2D材料设计潜在的OPT-Spintronics设备，以通过SHG生成旋转厅电流。
NbSe$_2$ is one of metallic two-dimensional (2D) transition-metal dichalcogenide (TMDC) materials. Because of broken crystal inversion symmetry, large spin splitting is induced by Ising-type spin-orbit coupling in odd-number-layered NbSe$_2$, but absent for even-number-layered NbSe$_2$ with the inversion symmetry. In this paper, we numerically calculate nonlinear optical charge and spin Hall conductivities of few-layered NbSe$_2$ based on an effective tight-binding model which includes $d_{z^2}$, $d_{x^2-y^2}$ and $d_{xy}$ orbitals of Nb atom. We show that the nonlinear optical Hall conductivity for second harmonic generation (SHG) process has nonvanishing value in odd-number-layered NbSe$_2$. Also, we provide nonlinear optical selection rule in few-layered NbSe$_2$ and their polarization dependences. In further, for even-number-layered case, the nonlinear optical Hall currents can be generated by applying electric fields which break inversion symmetry. We also discuss that the nonlinear optical Hall effect is expected to occur in TMDC materials in general. Thus, our results will serve to design potential opt-spintronics devices based on 2D materials to generate the spin Hall current by SHG.
