Enhanced Hybridization Sets the Stage for Electronic Nematicity in CeRhIn5

Abstract

High magnetic fields induce a pronounced in-plane electronic anisotropy in the tetragonal antiferromagnetic metal CeRhIn5 at H * 30 T for fields 20 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 CeRhIn5, a finite magnetic field component in the tetragonal ab-plane explicitly breaks the tetragonal (C4) symmetry of the lattice well below H * revealing a finite nematic susceptibility at low fields. A modest magnetostriction anomaly, dL/L = −1.8×10 −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.

Enhancement of the effective mass at high magnetic fields in CeRhIn5

“…While the critical fluctuations associated with phenomena such as CDW transitions and valence changes generally couple strongly to the lattice, those corresponding to SDW order commonly couple more weakly 28 . We note that weak anomalies have also been reported in the magnetostriction at B * when fields are applied at 11 • and 20 • to the c-axis 21,29 . It is possible that the magnetostriction change at B * is too weak to be resolved in our measurements with fields along the c-axis.…”

Magnetoelastics of High Field Phenomena in Antiferromagnets UO2 and CeRhIn5

“…Only data collected during field down sweep is presented, as magnet/probe mechanical vibrations precluded clear observation of this anomaly during field up sweep. A full discussion of data taken in a continuous magnetic field to 45T, confirming this anomaly as well as quantum magnetoelastic oscillations only hinted here, is presented elsewhere [12].…”

“…Meanwhile, the improved sensitivity of the FBG dilatometry technique in continuous magnetic fields reveal quite a nice quantum magnetoelastic oscillations in CeRhIn 5 . These magnetoelastic oscillations, recently reported for fields close to the c-axis [12], are a serendipitous finding that attests to the high quality of the single crystal samples at hand. Fig.…”

“…Moreover, recent experiments show that the electrical properties become strongly anisotropic and correlated to the field orientation, pointing to a possible electronic nematic state [11]. A few attempts have been made since to pinpoint this novel state [12], and more are needed to reach a satisfactory understanding.…”

Orientation of the ground-state orbital inCeCoIn5andCeRhIn5

“…Mixing of Zeeman-split ground and + 7 first excited crystalfield levels, in principle, could produce such a modest increase in the J z = | ± 5/2 contribution. Indeed, recent high-field magnetostriction [40] and nuclear magnetic resonance [41] measurements on CeRhIn 5 are consistent with this possibility that appears to be a significant contributing factor to fieldinduced Fermi-surface reconstruction in CeRhIn 5 subject to a magnetic field near 30 T.…”