Anisotropic Electronic Structure of the Kondo Semiconductor CeFe2Al10 Studied by Optical Conductivity

TL;DR

This study investigates the anisotropic electronic structure of CeFe2Al10 using temperature-dependent optical conductivity, revealing anisotropic hybridization gaps and Kondo temperatures that relate to magnetic transitions in related compounds.

Contribution

It provides the first detailed analysis of the anisotropic optical conductivity and hybridization gap behavior in CeFe2Al10, highlighting the anisotropic Kondo effect.

Findings

Anisotropic optical conductivity spectra along different crystal axes.

Observation of a hybridization gap at 55 meV at low temperatures.

Identification of anisotropic Kondo temperature and its relation to magnetic transitions.

Abstract

We report temperature-dependent polarized optical conductivity [$\sigma(\omega)$] spectra of CeFe$_2$Al$_{10}$, which is a reference material for CeRu$_2$Al$_{10}$ and CeOs$_2$Al$_{10}$ with an anomalous magnetic transition at 28 K. The $\sigma(\omega)$ spectrum along the b-axis differs greatly from that in the $ac$-plane, indicating that this material has an anisotropic electronic structure. At low temperatures, in all axes, a shoulder structure due to the optical transition across the hybridization gap between the conduction band and the localized $4f$ states, namely $c$-$f$ hybridization, appears at 55 meV. However, the gap opening temperature and the temperature of appearance of the quasiparticle Drude weight are strongly anisotropic indicating the anisotropic Kondo temperature. The strong anisotropic nature in both electronic structure and Kondo temperature is considered to be relevant the anomalous magnetic phase transition in CeRu$_2$Al$_{10}$ and CeOs$_2$Al$_{10}$.