D-wave superconductivity induced by proximity to the non-uniform chiral spin liquid on a square lattice

TL;DR

This paper demonstrates that a non-uniform chiral spin-liquid on a square lattice can induce D-wave superconductivity in nearby fermionic systems through gauge-field-mediated interactions.

Contribution

It provides evidence for a non-uniform chiral spin-liquid ground state and shows how it can induce superconductivity in adjacent fermionic environments.

Findings

Evidence of non-uniform chiral spin-liquid ground state.

Induction of attractive interactions leading to d-wave superconductivity.

Analytical description via topological fermionic Chern insulator and Chern-Simons theory.

Abstract

We use the tensor network algorithm to show evidences of a non-uniform chiral spin-liquid (CSL) ground state in a frustrated spin-1/2 model on a square lattice, in the regime of moat-like band structure of the lattice, i.e., a band with infinitely degenerate energy minima attained along a closed contour in the Brillouin zone. The analytical description of the state is given by the effective field theory of a topological square-lattice fermionic Chern insulator coupled to the Chern-Simons gauge field. The observed non-uniform CSL has a substantial effect on a nearby free-fermion environment. We show that, in the presence of arbitrarily small spin exchange interaction, the CSL can endow a gauge-field-modulated effective interaction between the environmental fermions. The induced effective interaction can be attractive within a significant parameter region, leading to an instability towards d-wave superconductivity in the fermionic bath.