Non-Fermi liquid behavior of doped Kondo insulator: The unique properties of CeRhSb$_{1-x}$Te$_x$

TL;DR

This paper investigates the effects of doping on the Kondo insulator CeRhSb, revealing universal scaling laws, the emergence of Griffiths phases, and evidence of topologically nontrivial properties through experimental and theoretical analysis.

Contribution

It provides a comprehensive analysis of how doping influences the Kondo insulator state and uncovers topological characteristics in CeRhSb and its doped variants.

Findings

Doping beyond 8-10% suppresses the Kondo insulator state.

Universal scaling law $ ext{chi} imes ho = ext{const.}$ is confirmed.

Magnetoresistance exhibits a $-B^2$ behavior indicating topological properties.

Abstract

It follows from our analysis of CeRhSb that the formation of Kondo insulator state due to the presence of the collective spin singlet state is strongly reduced by its doping with various dopants when their amount exceeds 8--10\%, regardless of whether they are substituted for Ce, Rh or Sb. A wide variety of experimental results (electrical resistivity $\rho$, magnetic susceptibility $\chi$, specific heat $C$, x-ray photoelectron spectroscopy) and theoretical investigations have convincingly demonstrated the proposed earlier scaling law $\chi\times\rho=const.$ in the Kondo insulator regime, which is universal for all known Kondo insulators. We also analyze the properties of the Griffiths--phase for CeRhSb when Pd substitutes Rh, or Sb is fractionally replaced by Te and Sn, whereas doping of Ce with La leads to the formation of magnetic cluster structure as a result of the Kondo hole effect. Magnetoresistance of CeRhSb and CeRhSb$_{0.98}$Te$_{0.02}$ as a function of the field $B$ shows a $-B^2$ behavior, which provides evidence for the topologically nontrivial nature of these compounds, as was previously predicted theoretically for CeRhSb on the basis on the band structure calculations.