Band Structure and Fermi Surface Nesting in $LaSb_2$

TL;DR

This study combines ARPES and DFT to explore LaSb$_2$'s electronic structure, revealing Fermi surface features, potential nesting vectors, and the subtle nature of its high-temperature CDW transition.

Contribution

It provides detailed experimental and theoretical analysis of LaSb$_2$'s electronic structure, highlighting the subtlety of its charge density wave transition and potential for future doping studies.

Findings

Fermi surface consists of small and large pockets with temperature-independent features.

Presence of a saddle point at -0.19 eV near $Gamma$.

No detectable signatures of the CDW transition at 355 K.

Abstract

We use high-resolution angle resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) to investigate the electronic structure of the charge density wave (CDW) system LaSb$_2$. This compound is among an interesting group of materials that manifests both a CDW transition and lower temperature superconductivity. We find the DFT calculations to be in good agreement with our ARPES data. The Fermi surface of LaSb$_2$ consists of two small hole pockets close to $\Gamma$ and four larger pockets near the Brillouin zone (BZ) boundary. The overall features of the Fermi surface do not vary with temperature. A saddle point is present at -0.19 $eV$ below the Fermi level at $\Gamma$. Critical points in band structure have more pronounced effects on a materials properties when they are located closer to the Fermi level, making doped LaSb$_2$ compounds a potential interesting subject of future research. Multiple peaks are present in the generalized, electronic susceptibility calculations indicating the presence of possible nesting vectors. We were not able to detect any signatures of the CDW transition at 355 K, pointing to the subtle nature of this transition. This is unusual, given that such a high transition temperature is expected to be associated with the presence of a large CDW gap. This is confirmed through investigation of the Fermi surface and through analysis of momentum distribution curves (MDC). It is possible that changes are subtle and occur below current sensitivity of our measurements.