Kondo exhaustion and conductive surface states in antiferromagnetic YbIr$_3$Si$_7$

TL;DR

This study reports on YbIr₃Si₇, a Kondo lattice material with fewer conduction electrons than local moments, exhibiting Kondo exhaustion, antiferromagnetic order, and potential topological surface states, revealing complex interplay in strongly correlated systems.

Contribution

It introduces YbIr₃Si₇ as a novel Kondo lattice exhibiting Kondo exhaustion and conductive surface states, expanding understanding of correlated electron behavior.

Findings

Electrical conductivity drops to zero at low temperatures due to Kondo exhaustion.

YbIr₃Si₇ exhibits antiferromagnetic order with T_N = 4.1 K.

Presence of potential topological surface states.

Abstract

The interplay of Kondo screening and magnetic ordering in strongly correlated materials containing local moments is a subtle problem.[1] Usually the number of conduction electrons matches or exceeds the number of moments, and a Kondo-screened heavy Fermi liquid develops at low temperatures.[2] Changing the pressure, magnetic field, or chemical doping can displace this heavy Fermi liquid in favor of a magnetically ordered state.[3,4] Here we report the discovery of a version of such a `Kondo lattice' material, YbIr$_3$Si$_7$, in which the number of free charge carriers is much less than the number of local moments. This leads to `Kondo exhaustion':[5] the electrical conductivity tends to zero at low temperatures as all the free carriers are consumed in the formation of Kondo singlets. This effect coexists with antiferromagnetic long-range order, with a N\'eel temperature $T\rm_N = 4.1\,{\rm K}$. Furthermore, the material shows conductive surface states with potential topological nature, and thus presents an exciting topic for future investigations.