# Electronic Structure and Magnetism in the Layered Triangular Lattice Compound CeAuAl$_4$Ge$_2$

## TL;DR

This study investigates the electronic structure and magnetic properties of CeAuAl$_4$Ge$_2$, revealing weak magnetic frustration, negligible Kondo correlations, and electronic behavior dominated by light $s$-, $p$-, and $d$- bands, with implications for geometric frustration research.

## Contribution

The paper provides detailed experimental and theoretical analysis of CeAuAl$_4$Ge$_2$, highlighting its weak magnetic frustration and electronic structure dominated by light bands, offering a new platform for studying geometric magnetic frustration without strong Kondo effects.

## Key findings

- Weak magnetic exchange interaction leads to marginal frustration.
- Negligible Kondo-driven electronic correlations observed.
- Electronic structure dominated by light $s$-, $p$-, and $d$- bands.

## Abstract

Results are reported for the $f$-electron intermetallic CeAuAl$_4$Ge$_2$, where the atomic arrangement of the cerium ions creates the conditions for geometric frustration. Despite this, magnetic susceptibility measurements reveal that the low temperature magnetic exchange interaction is weak, resulting in marginally frustrated behavior and ordering near $T_{\rm{M}}$ $\approx$ 1.4 K. This occurs within a metallic Kondo lattice, where electrical resistivity and heat capacity measurements show that the Kondo-driven electronic correlations are negligible. Quantum oscillations are detected in ac-magnetic susceptibility measurements and uncover small charge carrier effective masses. Electronic structure calculations reveal that when the experimentally observed antiferromagnetic exchange interaction and the on-$f$-site Coulomb repulsion (Hubbard) U are considered, the $f$-electron bands move away from the Fermi level, resulting in electronic behavior that is dominated by the $s$-, $p$-, and $d$- bands, which are all characterized by light electron masses. Thus, CeAuAl$_4$Ge$_2$ provides a starting point for investigating geometric magnetic frustration in a cerium lattice without strong Kondo hybridization, where calculations provide useful guidance.