Divergent Thermal Expansion and Grüneisen Ratio in a Quadrupolar Kondo Metal

Abstract

We report on the low-temperature thermal expansion and magnetostriction of the single-impurity quadrupolar Kondo candidate Y${}_{1-x}$Pr${}_x$Ir${}_2$Zn${}_{20}$. In the dilute limit, we find a quadrupolar strain that possesses a singular dependence on temperature $T$, ${\epsilon }_{\mathrm{u}}\sim H^2\log 1/T$, for a small but finite magnetic field $H$. Together with the previously reported anomalous specific heat $C$, this implies a quadrupolar Grüneisen ratio ${\Gamma }_u={\partial }_T{\epsilon }_{\mathrm{u}}/C\sim H^2/(T^2\log 1/T)$ whose divergence for finite $H$ is consistent with the scenario of a quadrupolar Kondo effect. In addition, we find a singular behavior of the isotropic strain ${\epsilon }_{\mathrm{B}}$ in zero magnetic field resulting in a divergence of both the volume thermal expansion and the volume Grüneisen parameter. We speculate that this behavior might be also induced by putative Kondo correlations via elastic anharmonicities or static strain disorder.

6 pages, 4 figures and supplemental material (10 pages, 6 figures)

References in corpus (7)

• Quantum Criticality in Heavy Fermion Metals
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Cited by in corpus (3)

• Inelastic neutron scattering study of crystalline electric field excitations in the caged compounds NdT2Zn20 (T = Co, Rh, and Ir)
• Probing magnetic-field-induced multipolar ordering through field-angle-resolved magnetostriction and thermal expansion in PrIr${}_2$Zn${}_{20}$
• Paramagnetic electron-nuclear spin entanglement in HoCo2Zn20