Spin fractionalization in a Kondo-lattice superconductor heterostructure

TL;DR

This paper investigates how proximity-induced superconductivity in Kondo-lattice heterostructures can lead to the fractionalization of spin excitations, offering new ways to understand and manipulate strongly correlated systems.

Contribution

It introduces a strong Kondo coupling expansion to analyze spin-1 excitations and demonstrates how superconducting pairing can induce fractionalization of paramagnons.

Findings

Paramagnons are stable at strong Kondo coupling.

Superconducting pairing can promote fractionalization of spin excitations.

Results suggest experimental verification via neutron scattering.

Abstract

Kondo lattices are one of the classic models of strongly correlated systems where despite a long history, a full understanding of the excitation spectra is still not available. Here we propose that recent progress in engineering heterostructures can be leveraged to gain insight into and even tune this spectra. We use a strong Kondo coupling expansion to study spin-1 excitations of a Kondo lattice in both one and two-dimension to see whether or not paramagnons in a Kondo insulator fractionalize into spin-1/2 excitations. We show that while paramagnons are stable in the strong Kondo coupling limit, presence of sufficient proximity-induced superconducting pairing can favor fractionalization. Our results can be checked using a neutron scattering study of Kondo lattice heterostructures and paves the way toward engineering strongly correlated electronic systems.