Anomalous Metal-Insulator Transition in Filled Skutterudite CeOs$_4$Sb$_{12}$

TL;DR

This study models the anomalous metal-insulator transition in CeOs$_4$Sb$_{12}$ using a tight-binding approach, revealing a spin density wave phase driven by Fermi surface nesting that aligns with experimental observations.

Contribution

It introduces a theoretical model incorporating Coulomb interactions to explain the magnetic transition in filled skutterudite CeOs$_4$Sb$_{12}$, highlighting the role of Fermi surface nesting.

Findings

Spin density wave transition occurs at Q=(1,0,0) due to Fermi surface nesting.

Magnetic field enhances the SDW phase, consistent with experiments.

Semimetallic band structure with small electron and hole pockets is crucial.

Abstract

Anomalous metal-insulator transition observed in filled skutterudite CeOs$_4$Sb$_{12}$ is investigated by constructing the effective tight-binding model with the Coulomb repulsion between f electrons. By using the mean field approximation, magnetic susceptibilities are calculated and the phase diagram is obtained. When the band structure has a semimetallic character with small electron and hole pockets at $\Gamma$ and H points, a spin density wave transition with the ordering vector $\mathbf{Q}=(1,0,0)$ occurs due to the nesting property of the Fermi surfaces. Magnetic field enhances this phase in accord with the experiments.