Non-Fermi liquid regime in metallic pyrochlore iridates: Quantum Griffiths singularities

TL;DR

This paper explores non-Fermi liquid behavior in metallic pyrochlore iridates caused by disorder and quantum Griffiths singularities, revealing a complex interplay of Kondo and RKKY interactions.

Contribution

It demonstrates the existence of a quantum Griffiths phase in disordered Pr2Ir2O7, highlighting the coexistence of Kondo screening and magnetic rare regions.

Findings

Non-Fermi liquid behavior observed in transport and thermodynamics.

Magnetic susceptibility shows power law divergence at T=0.

Evidence of a quantum Griffiths phase with coexisting magnetic states.

Abstract

We investigate the interplay of Kondo and RKKY coupling in presence of disorder by chemically substituting local moment Cr^{3+} at the Ir sublattice in the metallic Pr_{2}Ir_{2}O_{7}. We find evidence of non-Fermi liquid (NFL) behaviour in the transport and thermodynamic measurements at low temperature. Specifically, the magnetic susceptibility exhibits power law divergence at T=0. The nonanalytic temperature and magnetic-field dependence of magnetic susceptibility and the associated scaling suggest existence of a two-fluid system consisting of Kondo-screened paramagnetic metal coexisting with magnetically ordered rare regions dominated by inter-impurity interaction, similar to quantum critical Griffiths phase.