Observation of momentum dependent charge density wave gap in EuTe4

TL;DR

This paper investigates the momentum-dependent charge density wave gap in EuTe4 using DFT calculations, ARPES, and heat capacity measurements, revealing anisotropic electronic structure and magnetic phase behavior.

Contribution

It provides the first combined theoretical and experimental analysis of the directional CDW gap and its relation to the Fermi surface in EuTe4.

Findings

CDW gap observed at the Fermi level with anisotropic maximum and minimum.

Fermi surface nesting induces directional CDW ordering.

Magnetic phase diagram constructed near Neel temperature.

Abstract

The occurrence of charge density wave (CDW) phenomena, particularly in low dimensional rare-earth chalcogenides, has attracted substantial research interest. Among these materials, EuTe4, which features multiple Te layers and a single Eu-Te layer, serves as a promising platform to study the interplay between CDW order and 4f electron configurations, including magnetism. In this study, First principles based density functional theory (DFT) calculations were carried out to investigate the electronic band structure modifications arising from CDW modulation. Angle resolved photoemission spectroscopy (ARPES) revealed the emergence of a CDW gap at the Fermi level, as well as hybridization induced gap features at lower binding energies. The low lying CDW gap reaches its maximum along the Gamma-Y high-symmetry direction and a minimum along GX reflecting the anisotropic nature of the electronic structure. We also performed low temperature heat capacity measurements in applied magnetic fields near the Neel temperature (TN ~ 6.9 K) to construct the magnetic phase diagram of EuTe4. This study provides valuable insight into the directional dependent evolution of the Fermi surface nesting induced CDW ordering, along with other observed gap openings within this system.