The filled skutterudite CeOs$_{4}$As$_{12}$: a hybridization gap semiconductor

TL;DR

This study investigates the electronic and magnetic properties of the filled skutterudite CeOs4As12, revealing a hybridization gap insulating state driven by f-electron conduction electron interactions, with evidence of valence fluctuations and Kondo behavior.

Contribution

The paper provides detailed experimental characterization of CeOs4As12, demonstrating its hybridization gap and correlated electron behavior, which advances understanding of f-electron hybridization in skutterudites.

Findings

CeOs4As12 exhibits a hybridization gap of ~73 K.

Valence fluctuations or Kondo behavior dominate down to 135 K.

Low-temperature data show a weakly magnetic or nonmagnetic ground state.

Abstract

X-ray diffraction, electrical resistivity, magnetization, specific heat, and thermoelectric power measurements are presented for single crystals of the new filled skutterudite compound {\CeOsAs}, which reveal phenomena that are associated with f - electron - conduction electron hybridization. Valence fluctuations or Kondo behavior dominates the physics down to $T$ $\sim$ 135 K. The correlated electron behavior is manifested at low temperatures as a hybridization gap insulating state. The small energy gap $\Delta$$_1$/k$_B$ $\sim$ 73 K, taken from fits to electrical resistivity data, correlates with the evolution of a weakly magnetic or nonmagnetic ground state, which is evident in the magnetization data below a coherence temperature $T$$_{coh}$ $\sim$ 45 K. Additionally, the low temperature electronic specific heat coefficient is small, $\gamma$ $\sim$ 19 mJ/mol K$^2$. Some results for the nonmagnetic analogue compound {\LaOsAs} are also presented for comparison purposes.