Spin fluctuations steer the electronic behavior in the FeSb$_{3}$ skutterudite

TL;DR

This study investigates how spin fluctuations influence the electronic properties of FeSb₃ skutterudite, revealing complex magnetic states and their impact on electronic structure, with implications for thermoelectric and spintronic applications.

Contribution

It introduces a detailed theoretical analysis of spin fluctuations in FeSb₃, highlighting their role in electronic behavior and identifying limitations of simple magnetic models.

Findings

Paramagnetic fluctuations induce a 61 meV gap in FeSb₃.

Multiple magnetic configurations, including antiferromagnetic metallic ground state.

Low Nél temperature suggests additional factors like stoichiometry influence magnetic behavior.

Abstract

Skutterudites are promising materials for thermoelectric and spintronics applications. Here we explore spin fluctuations in the FeSb$_{3}$ skutterudite and their effect on its electronic structure using Hubbard-corrected density-functional theory calculations. We identify multiple magnetic and charge-disproportionated configurations, with an antiferromagnetic metallic ground state. Paramagnetic fluctuations modeled through a special quasirandom spin structure open a 61 meV gap, consistent with experiments. This state features non-degenerate spin channels and band-avoided crossings, resembling a Luttinger-compensated ferrimagnet. Mapping the electronic structure to a Heisenberg Hamiltonian fails to explain the low N\'eel temperature ($\lesssim$10 K), suggesting that factors such as stoichiometry and magnetic exchange frustration may play an important role, calling for more detailed experimental investigations.