Low-carrier density and fragile magnetism in a Kondo lattice system

TL;DR

This paper reveals a new mechanism for Kondo semimetals arising from low carrier density conduction electrons, demonstrated in Yb3Ir4Ge13, showing fragile magnetism and tunable non-Fermi liquid behavior, expanding the understanding of correlated states in semimetals.

Contribution

It introduces a novel pathway for Kondo semimetals from low-carrier conduction electrons, supported by experimental evidence in Yb3Ir4Ge13 and Lu3Ir4Ge13, linking to recent theoretical models.

Findings

Kondo effect in low-carrier-density semimetals demonstrated in Yb3Ir4Ge13.

Fragile magnetism observed at very low temperatures.

Magnetic properties tunable via Lu-for-Yb substitution.

Abstract

Kondo-based semimetals and semiconductors are of extensive current interest as a viable platform for strongly correlated states. It is thus important to understand the routes towards such dilute-carrier correlated states. One established pathway is through Kondo effect in metallic non-magnetic analogues. Here we advance a new mechanism, through which Kondo-based semimetals develop out of conduction electrons with a low carrier-density in the presence of an even number of rare-earth sites. We demonstrate this effect by studying the Kondo material Yb3Ir4Ge13 along with its closed-f-shell counterpart, Lu3Ir4Ge13. Through magnetotransport, optical conductivity and thermodynamic measurements, we establish that the correlated semimetallic state of Yb3Ir4Ge13 below its Kondo temperature originates from the Kondo effect of a low carrier conduction-electron background. In addition, it displays fragile magnetism at very low temperatures, which, in turn, can be tuned to a non Fermi liquid regime through Lu-for-Yb substitution. These findings are connected with recent theoretical studies in simplified models. Our results open an entirely new venue to explore the strong correlation physics in a semimetallic environment.