High temperature antiferromagnetism in Yb based heavy fermion systems proximate to a Kondo insulator

TL;DR

This paper reports the discovery of high-temperature antiferromagnetism at 20 K in a Yb-based heavy fermion system, achieved through Mn substitution, revealing new insights into Yb magnetism and Kondo insulator proximity.

Contribution

The study demonstrates that Mn substitution in $ extalpha$-YbAlB$_{4}$ induces a record high antiferromagnetic transition temperature and transforms its electronic state.

Findings

Antiferromagnetic transition at 20 K in Yb-based compound

Transformation into a Kondo insulator-like state

Record high transition temperature for Yb systems

Abstract

Given the parallelism between the physical properties of Ce and Yb based magnets and heavy fermions due to the electron-hole symmetry, it has been rather odd that the transition temperature of the Yb based compounds is normally very small, as low as $\sim$ 1 K or even lower, whereas Ce counterparts may often have the transition temperature well exceeding 10 K. Here, we report our experimental discovery of the transition temperature reaching 20 K for the first time in a Yb based compound at ambient pressure. The Mn substitution at the Al site in an intermediate valence state of $\alpha$-YbAlB$_{4}$ not only induces antiferromagnetic transition at a record high temperature of 20 K but also transforms the heavy fermion liquid state in $\alpha$-YbAlB$_{4}$ into a highly resistive metallic state proximate to a Kondo insulator.