Hybridization-driven gap in U3Bi4Ni3: a 209Bi NMR/NQR study

TL;DR

This study uses 209Bi NMR and NQR to investigate the electronic properties of U3Bi4Ni3, revealing a spin gap and hyperfine field evolution characteristic of a hybridization-driven Kondo insulator.

Contribution

It provides the first detailed NMR/NQR analysis of U3Bi4Ni3, highlighting the spin gap and hyperfine interactions in a 5f electron hybridized Kondo insulator.

Findings

Spin gap of 220 K identified from relaxation rates

Temperature-dependent Knight shift indicates 5f electron hybridization

Hyperfine fields evolve with temperature, reflecting electronic structure changes

Abstract

We report 209Bi NMR and NQR measurements on a single crystal of the Kondo insulator U3Bi4Ni3. The 209Bi nuclear spin-lattice relaxation rate ($T_1^{-1}$) shows activated behavior and is well-fit by a spin gap of 220 K. The 209Bi Knight shift (K) exhibits a strong temperature dependence arising from 5f electrons, in which K is negative at high temperatures and increases as the temperature is lowered. Below 50 K, K shows a broad maximum and decreases slightly upon further cooling. Our data provide insight into the evolution of the hyperfine fields in a fully gapped Kondo insulator based on 5f electron hybridization.