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arXiv 2109.08348cond-mat.str-elcond-mat.mtrl-sci
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1 T- NbS2层状电荷密度波相位的堆积效应和库仑关联

Stacking effect and Coulomb correlation in layered charge density wave phase of 1T-NbS2

Wei Wang, Chen Si, Wen Lei, Feng Xiao, Yunhui Liu, Carmine Autieri, Xing Ming

摘要:

基于第一性原理计算,采用二维电荷密度波(CDW)方法,研究了层状vdW材料1 T-NbS 2中电子-电子关联与堆垛效应的相互作用.在不考虑库仑相关的情况下,我们发现了两种能量上有利的面外堆积结构:一种是单层堆积结构的金属相,另一种是双层堆积结构的带绝缘体。即使考虑了库仑关联,这两个能量有利的堆垛阶仍然比其他堆垛阶稳定得多。此外,随着库仑相互作用的增加,双层堆叠结构从能带绝缘体转变为反铁磁绝缘体,而单层堆叠结构经历了Slater-Mott金属-绝缘体转变,这表明电子-电子关联相互作用的作用不可忽视.此外,电子结构和磁基态在不同的堆叠结构之间发生了剧烈的变化,这为通过改变堆叠顺序来调节电子结构和层间磁相互作用提供了一个平台。与广泛接受的Mott局域化作为层状过渡金属二硫属化物的CDW相中间隙形成背后的驱动力的情况相反,我们的结果不仅突出了堆叠顺序在1 T-NbS 2的电子结构中的关键作用,而且还揭示了库仑相互作用在不同堆叠排列中的不同影响。

英文摘要:

Based on first-principles calculations, we explored the interplay between stacking effect and electron-electron correlation in the layered vdW material of bulk 1T-NbS2 with a 2D charge density wave (CDW) order. Without considering the Coulomb correlation, two energetically favorable out-of-plane stacking configurations are identified: one is a metallic phase with a single-layer stacking pattern, another is a band insulator with a paired-bilayer stacking configuration. Even though the Coulomb correlation is taken into account, the two energetic favorable stacking orders are still far more stable than other stacking orders. Furthermore, increasing the Coulomb interaction, the paired-bilayer stacking configuration transforms from nonmagnetic band insulator to antiferromagnetic insulator, while the single-layer stacking undergoes a Slater-Mott metal-insulator transition, which indicates the non-negligible role of electron-electron correlation interactions. In addition, the electronic structure and magnetic ground state change drastically among different stacking configurations, providing a platform to tune the electronic structures and interlayer magnetic interactions by altering the stacking order. In contrast to the widely accepted scenario of Mott localization as the driving force behind the gap formation in the CDW phase of layered transition metal dichalcogenides, our results not only highlight the crucial role of stacking order in the electronic structures of 1T-NbS2, but also shed fresh light on the distinct effects of Coulomb interaction in different stacking arrangements.

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