Transport properties in CeOs$_{4}$Sb$_{12}$: Possibility of the ground state being semiconducting

TL;DR

This study investigates the transport properties of CeOs$_{4}$Sb$_{12}$, revealing unusual temperature dependencies and a likely spin density wave transition, suggesting the ground state may be semiconducting rather than a Kondo insulator.

Contribution

It provides new insights into the phase transition and electronic structure of CeOs$_{4}$Sb$_{12}$ through detailed transport measurements and phase diagram analysis.

Findings

Unusual T dependence of resistivity and Hall coefficient over a wide temperature range.

Clear transport anomaly associated with the phase transition, likely a spin density wave.

Magnetic fields suppress resistivity and Hall resistivity, indicating changes in electronic structure.

Abstract

We have measured both magnetoresistance and Hall effect in CeOs$_4$Sb$_{12}$ to clarify the large resistivity state ascribed to the Kondo insulating one and the origin of the phase transition near 0.9 K reported in the specific heat measurement. We found unusual temperature ($T$) dependence both in the electrical resistivity $\rho\sim T^{-1/2}$ and the Hall coefficient $R_{\rm H}\sim T^{\rm -1}$ over the wide temperature range of about two order of magnitude below $\sim30$ K, which can be explained as a combined effect of the temperature dependences of carrier density and carrier scattering by spin fluctuation. An anomaly related with the phase transition has been clearly observed in the transport properties, from which the $H-T$ phase diagram is determined up to 14 T. Taking into account the small entropy change, the phase transition is most probably the spin density wave one. Both the electrical resistivity and Hall resistivity at 0.3 K is largely suppressed about an order of magnitude by magnetic fields above $\sim3$ T, suggesting a drastic change of electronic structure and a suppression of spin fluctuations under magnetic fields.