论文标题
抗铁磁性诱导的二阶非线性光学响应的中心对称双层cri $ _3 $
Antiferromagnetism-induced second-order nonlinear optical responses of centrosymmetric bilayer CrI$_3$
论文作者
论文摘要
Antiferromagnetism (AF) in AB'-stacked centrosymmetric bilayer (BL) CrI$_3$ breaks both spatial inversion ($P$) and time-reversal ($T$) symmetries but maintains the combined $PT$ symmetry, thus inducing novel second-order nonlinear optical (NLO) responses such as second-harmonic generation (SHG), linear electric-optic effect （LEO）和大量光伏效应（BPVE）。在这项工作中，我们根据密度功能理论计算了AF诱导的BL CRI $ _3 $的NLO响应，并使用广义梯度近似（GGA）加上现场库仑相关（U），即GGA+U方法。有趣的是，我们发现AF BL CRI $ _3 $中的磁性SHG，LEO和Photocrent是巨大的，相当甚至比众所周知的非磁性非中性非对称半导体。例如，计算出的SHG系数的数量级与MOS $ _2 $单层（ML）的数量级，这是NLO设备最有希望的2D材料。计算出的LEO系数几乎是MOS $ _2 $ ml的三倍。 CRI $ _3 $ BL中计算出的NLO光电流是迄今为止BPVE材料预测的最大值之一。另一方面，与非磁性半导体不同，AF BL CRI $ _3 $中的NLO响应是非偏型的，并且也可以通过旋转磁化方向而切换。因此，我们有趣的发现表明，AF BL CRI $ _3 $不仅将为探索低维磁性的新物理学提供一个有价值的平台，而且在磁NLO和LEO设备中具有有希望的应用，例如频率转换，电光开关，光信号调节器以及高能量转换效率的光电效应光电效应光电效应Solar solar solar solar solar solar cill。
Antiferromagnetism (AF) in AB'-stacked centrosymmetric bilayer (BL) CrI$_3$ breaks both spatial inversion ($P$) and time-reversal ($T$) symmetries but maintains the combined $PT$ symmetry, thus inducing novel second-order nonlinear optical (NLO) responses such as second-harmonic generation (SHG), linear electric-optic effect (LEO) and bulk photovoltaic effect (BPVE). In this work, we calculate AF-induced NLO responses of the BL CrI$_3$ based on the density functional theory with the generalized gradient approximation (GGA) plus onsite Coulomb correlation (U), i.e., the GGA+U method. Interestingly, we find that the magnetic SHG, LEO and photocurrent in the AF BL CrI$_3$ are huge, being comparable or even larger than that of the well-known nonmagnetic noncentrosymmetric semiconductors. For example, the calculated SHG coefficients are in the same order of magnitude as that of MoS$_2$ monolayer (ML), the most promising 2D material for NLO devices. The calculated LEO coefficients are almost three times larger than that of MoS$_2$ ML. The calculated NLO photocurrent in the CrI$_3$ BL is among the largest values predicted so far for the BPVE materials. On the other hand, unlike nonmagnetic semiconductors, the NLO responses in the AF BL CrI$_3$ are nonreciprocal and also switchable by rotating magnetization direction. Therefore, our interesting findings indicate that the AF BL CrI$_3$ will not only provide a valuable platform for exploring new physics of low-dimensional magnetism but also have promising applications in magnetic NLO and LEO devices such as frequency conversion, electro-optical switches, and light signal modulators as well as high energy conversion efficiency photovoltaic solar cells.
