Partial Kondo Screening and Anomalous Thermal Conductance

TL;DR

This paper explores the phase diagram of a frustrated Kondo-Heisenberg model on a honeycomb lattice, revealing partial Kondo screening, a fractionalized superconductor, and anomalous thermal conductance behaviors due to magnetic fluctuations.

Contribution

It introduces the concept of a fractionalized superconductor (SC*) in a frustrated Kondo lattice and analyzes its properties using mean-field theory and exact diagonalization.

Findings

Partial Kondo screening occurs in the frustrated regime.

Identification of a fractionalized superconductor (SC*).

Anomalous thermal conductance behavior in the SC* phase.

Abstract

The frustrated magnetism on the Kondo lattice system motivates intriguing Kondo-breakdown beyond the traditional Doniach scenario. Among them, the fractionalized Fermi liquid (FL*) has drawn a particular interest by virtue of its fractionalized nature. Here, we study the phase diagram of $J_{1}$-$J_{2}$ Kondo-Heisenberg model on a honeycomb lattice at a quarter filling. Employing the slave-fermion mean-field theory with $d \pm id$ spin liquid ansatz and exact diagonalization, we discuss the emergence of partial Kondo screening in the frustrated regime with comparable $J_{1}$ and $J_{2}$, and the fractionalized superconductor (SC*) which is superconductor analogy of the FL*. Due to the larger number of local spin moments than itinerant electrons, the magnetic fluctuation is still significant even in the strong-coupling limit, which influences the thermodynamic and transport properties qualitatively. In particular, we estimate the thermal conductance to probe the low-energy excitation and show the anomalous behaviour in the SC* phase contrast to the conventional superconductors.