Orbital-selective charge-density wave in TaTe$_4$

TL;DR

This study combines experimental and theoretical methods to reveal the orbital-dependent electronic structure and large CDW gap in TaTe$_4$, highlighting the complex interplay of orbitals, lattice, and electron interactions in this quasi-one-dimensional CDW material.

Contribution

It provides the first detailed analysis of the orbital nature of the CDW gap and metallic states in TaTe$_4$ using high-resolution ARPES and ab-initio calculations.

Findings

CDW gap as large as 290 meV persists up to 500 K

Large CDW gap mainly involves out-of-plane orbitals

Remnant metallic states originate from in-plane orbitals

Abstract

TaTe$_4$, a metallic charge-density wave (CDW) material discovered decades ago, has attracted renewed attention due to its rich interesting properties such as pressure-induced superconductivity and candidate non-trivial topological phase. Here, using high-resolution angle-resolved photoemission spectroscopy and ab-initio calculation, we systematically investigate the electronic structure of TaTe$_4$. At 26 K, we observe a CDW gap as large as 290 meV, which persists up to 500 K. The CDW-modulated band structure shows a complex reconstruction that closely correlates with the lattice distortion. Inside the CDW gap, there exist highly dispersive energy bands contributing to the remnant Fermi surface and metallic behavior in the CDW state. Interestingly, our ab-initio calculation reveals that the large CDW gap mainly opens in the electronic states with out-of-plane orbital components, while the in-gap metallic states originate from in-plane orbitals, suggesting an orbital texture that couples with the CDW order. Our results shed light on the interplay between electron, lattice, and orbital in quasi-one-dimensional CDW materials.