Enhanced hybridization sets the stage for electronic nematicity in CeRhIn5

TL;DR

This study reveals that high magnetic fields induce electronic nematicity in CeRhIn5, driven by enhanced hybridization of 4f electrons, with observable lattice and Fermi surface changes indicating a crossover to a nematic phase.

Contribution

The paper demonstrates the emergence of electronic nematicity in CeRhIn5 under high magnetic fields, linking it to increased 4f hybridization and lattice anisotropy, a novel insight into heavy-fermion behavior.

Findings

Finite in-plane electronic anisotropy at fields above 30 T.

Magnetostriction anomaly at 31 T indicating nematic crossover.

Fermi surface reconstruction confirmed by quantum oscillations.

Abstract

High magnetic fields induce a pronounced in-plane electronic anisotropy in the tetragonal antiferromagnetic metal CeRhIn$_{5}$ at $H^{*} \gtrsim 30$ T for fields $\simeq 20^{\mathrm{o}}$ off the $c$-axis. Here we investigate the response of the underlying crystal lattice in magnetic fields to $45$ T via high-resolution dilatometry. Within the antiferromagnetic phase of CeRhIn$_{5}$, a finite magnetic field component in the tetragonal $ab$-plane explicitly breaks the tetragonal ($C_{4}$) symmetry of the lattice well below $H^{*}$ revealing a finite nematic susceptibility at low fields. A modest magnetostriction anomaly, $dL/L = -1.8 \times 10^{-6}$, at $H^{*} = 31$ T hence presumably marks the crossover to a fluctuating nematic phase with large electronic nematic susceptibility. Magnetostriction quantum oscillations confirm a Fermi surface change at $H^*$ with the emergence of new orbits. By analyzing the field-induced change in the crystal-field ground state, we conclude that the in-plane Ce $4f$ hybridization is enhanced at $H^*$, carrying the in-plane $f$-electron anisotropy to the Fermi surface. We argue that the nematic behavior observed in this prototypical heavy-fermion material is of electronic origin, and is driven by the hybridization between $4f$ and conduction electrons.