论文标题
轨道选择带杂交在电荷密度波转换$ _2 $中
Orbital-selective Band Hybridisation at the Charge Density Wave Transition in Monolayer TiTe$_2$
论文作者
论文摘要
单层1T $ _2 $中出现了异常的$（2 \ times2）$电荷密度波（CDW）阶段，该相位对于散装化合物不存在，其起源仍然很熟悉。在这里，我们使用与温度依赖性角度分辨光发射光谱法研究了整个CDW转变的电子带结构的演化。我们的研究揭示了发生在CDW相跃迁处的反折叠传导和价带之间的轨道选择带杂交，这又导致了CDW过渡的支撑。对于散装化合物，我们展示了由于电子带结构的三维性，包括通过$ k_z $依赖性的带反转，几乎完全抑制了这种能量增益，从而切换了价值状态的轨道特征。因此，我们的研究阐明了如何使用对电子尺寸的控制来触发2D材料中新的集体状态的出现。
An anomalous $(2\times2)$ charge density wave (CDW) phase emerges in monolayer 1T-TiTe$_2$ which is absent for the bulk compound, and whose origin is still poorly understood. Here, we investigate the electronic band structure evolution across the CDW transition using temperature-dependent angle-resolved photoemission spectroscopy. Our study reveals an orbital-selective band hybridisation between the backfolded conduction and valence bands occurring at the CDW phase transition, which in turn leads to a significant electronic energy gain, underpinning the CDW transition. For the bulk compound, we show how this energy gain is almost completely suppressed due to the three-dimensionality of the electronic band structure, including via a $k_z$-dependent band inversion which switches the orbital character of the valence states. Our study thus sheds new light on how control of the electronic dimensionalilty can be used to trigger the emergence of new collective states in 2D materials.
