[论文解读] Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2

Yi Chen, Wei Ruan+19 more|arXiv (Cornell University)|Apr 24, 2019

2D Materials and Applications参考文献 47被引用 35

一句话总结

本文表明单层 1T-TaSe2 体现出稳健的莫特绝缘态及新颖的轨道纹理，层间耦合在双层/三层形式中削弱了该态，使用时空分辨的光谱学（STM 和 ARPES）并辅以理论分析。

ABSTRACT

Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunneling microscopy and angle-resolved photoemission. Our combined experimental and theoretical study indicates that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by novel orbital texture. Inclusion of interlayer coupling weakens the insulating phase in 1T-TaSe2, as seen by strong reduction of its energy gap and quenching of its correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. Our results establish single-layer 1T-TaSe2 as a useful new platform for investigating strong correlation physics in two dimensions.

研究动机与目标

• 激发利用范德华材料在二维中研究莫特物理的兴趣。
• 表征单层及少层 1T-TaSe2 的局部电子性质。
• 识别与相关驱动的绝缘态相关的轨道纹理。
• 评估层间耦合对莫特态及轨道纹理的影响。

提出的方法

• 使用空间分辨的扫描隧道显微镜来探测局部电子结构。
• 应用角分辨光电子能谱来绘制动量分辨的电子态。
• 将实验数据与理论建模结合起来以解释由相关性引起的绝缘行为。
• 研究层间耦合如何改变多层样品中的能隙和轨道纹理。

实验结果

研究问题

• RQ1 单层 1T-TaSe2 是否由于电子相关性而具备稳健的莫特绝缘态？
• RQ2 伴随莫特绝缘体的轨道纹理的本质是什么？
• RQ3 层间耦合如何影响双层和三层样品中的绝缘带隙和轨道纹理？
• RQ4 单层 1T-TaSe2 能否作为在二维中研究强相关物理的平台？

主要发现

• 单层 1T-TaSe2 显示出由电子相关性驱动的稳健莫特绝缘态。
• 绝缘态伴随可通过光谱学检测到的新颖轨道纹理。
• 层间耦合削弱了莫特绝缘相，在双层/三层样品中导致能隙显著减小和轨道纹理的抑制。
• 该结果将单层 1T-TaSe2 定位为二维强相关物理的有用平台。