论文标题
大型带中二维铁电gaxy（x = se，te; y = cl，br，i）家族中的大型带旋转极化
Large band splitting with tunable spin polarization in two-dimensional ferroelectric GaXY (X= Se, Te; Y= Cl, Br, I) family
论文作者
论文摘要
人们普遍认为，非中心对称材料中的自旋轨道耦合效应会导致谱带分裂和动量空间中的非平凡自旋极化。但是，在某些情况下，可能发生分裂带中的零净自旋极化，被称为带有消失的自旋极化（BSVSP）效应的带，受到第一个Brillouin区域波矢量的非质量极点点对称性的保护[Liu等。 al。，纳特。社区。 \ textbf {10}，5144（2019）]。在本文中，通过使用第一原理计算，我们表明BSVSP效应以二维（2D）非晶状体形态GA $ xy $ xy $（$ x $ = se，te； $ y $ = cl，br，i）家庭，是具有平面性铁层内部的2D 2D材料的新类。以GateCl单层为代表性的例子，我们沿着位于传导带最小值的$ x-m $线的分裂带中的BSVSP效应。通过使用基于对称分析的$ \ vec {k} \ cdot \ vec {p} $ hamiltonian衍生得出的hamiltonian，我们澄清了这种效果源于取消局部旋转极化，该局部旋转极化是由非plesudo polar polar $ c_ {2v} $ coint copt opt opt opt opt copt opt opt opt opt opt copt copt copt copt symmetry沿着$ x-m $ x-m $ $ x-m $ line的对称。重要的是，我们发现可以通过施加平面外电场来有效地诱导自旋极化，这表明可以使用用于自旋旋转应用的电气可调的自旋极化是合理的。
It has been generally accepted that the spin-orbit coupling effect in noncentrosymmetric materials leads to the band splitting and non-trivial spin polarization in the momentum space. However, in some cases, zero net spin polarization in the split bands may occurs, dubbed as the band splitting with vanishing spin polarization (BSVSP) effect, protected by non-pseudo-polar point group symmetry of the wave vector in the first Brillouin zone [Liu et. al., Nat. Commun. \textbf{10}, 5144 (2019)]. In this paper, by using first-principles calculations, we show that the BSVSP effect emerges in two-dimensional (2D) nonsymmorphic Ga$XY$ ($X$= Se, Te; $Y$= Cl, Br, I) family, a new class of 2D materials having in-plane ferroelectricity. Taking the GaTeCl monolayer as a representative example, we observe the BSVSP effect in the split bands along the $X-M$ line located in the proximity of the conduction band minimum. By using $\vec{k}\cdot\vec{p}$ Hamiltonian derived based on the symmetry analysis, we clarify that such effect is originated from the cancellation of the local spin polarization, enforced by non-pseudo-polar $C_{2v}$ point group symmetry of the wave vector along the $X-M$ line. Importantly, we find that the spin polarization can be effectively induced by applying an external out-of-plane electric field, indicating that an electrically tunable spin polarization for spintronic applications is plausible.
