Fingerprints for anisotropic Kondo lattice behavior in the quasiparticle dynamics of the kagome metal Ni$_3$In

TL;DR

This study uses Raman scattering and first-principles calculations to reveal an anisotropic Kondo crossover in Ni$_3$In, characterized by phonon and electronic signatures indicating a transition from incoherent to coherent quasiparticle behavior below 50 K.

Contribution

It provides the first detailed Raman evidence of anisotropic Kondo lattice behavior and quasiparticle dynamics in the kagome metal Ni$_3$In, highlighting an electronic crossover below 50 K.

Findings

Observation of phonon renormalization below 50 K indicating Kondo screening

Detection of anisotropic electronic continuum changes with temperature

Evidence for an anisotropic incoherent-coherent Kondo crossover

Abstract

We present a temperature- and polarization-resolved phononic and electronic Raman scattering study in combination with the first-principles calculations on the kagome metal Ni$_3$In with anisotropic transport properties and non-Fermi liquid behavior. At temperatures below 50 K and down to 2 K, several Raman phonon modes, including particularly an interlayer shear mode, exhibit appreciable frequency and linewidth renormalization, reminiscent of the onset of the Kondo screening without an accompanying structural or magnetic phase transition. In addition, a low-energy electronic continuum observed in polarization perpendicular to the kagome planes reveals strong temperature dependence below 50 K, implying thermal depletion of incoherent quasiparticles, while the in-plane continuum remains invariant. These concomitant electronic and phononic Raman signatures suggest that Ni$_3$In undergoes an anisotropic electronic crossover from an incoherent to a coherent Kondo lattice regime below 50 K. We discuss the origin of the anisotropic incoherent-coherent crossover in association with the possible anisotropic Kondo hybridization involving localized Ni-$3d_{xz}$ flat-band electrons.