Interplay of electronic structure and unusual development in crystal structure of YbAuIn and Yb$_{3}$AuGe$_{2}$In$_{3}$

TL;DR

This study uses first-principles DFT calculations to explore how electronic valency states of Yb influence the unusual crystal structure parameters of YbAuIn and Yb₃AuGe₂In₃, revealing a link between valency and lattice expansion.

Contribution

It demonstrates the relationship between Yb valency states and structural parameters, providing insight into the electronic-structural interplay in these compounds.

Findings

YbAuIn is an intermediate valent system with Yb 4f state at Fermi level.

Yb₃AuGe₂In₃ is closer to integer valency with fully occupied Yb 4f states.

Expansion of the c-parameter in Yb₃AuGe₂In₃ is due to larger divalent Yb size.

Abstract

First-principles calculations within the DFT are employed to investigate the relationship between the electronic structure and the unexpected features of the hexagonal cell parameters of YbAuIn and Yb$_{3}$AuGe$_{2}$In$_{3}$. Calculations indicate that YbAuIn is an intermediate valent system with one Yb 4\textit{f} state pinned to the Fermi level, while Yb$_{3}$AuGe$_{2}$In$_{3}$ is closer to integer valency with all Yb 4\textit{f} states occupied. Structural relaxations performed on LaAuIn and LuAuIn analogs reveal that expansion of the \textit{c}-parameter in Yb$_{3}$AuGe$_{2}$In$_{3}$ is attributable to larger size of the divalent Yb compared with intermediate valent Yb.