Detect Spinons via Spin Transport

TL;DR

This paper proposes a method to detect spinons in quantum spin liquids by measuring spin transport, using nonequilibrium Green functions to distinguish different Mott insulators through spin current responses.

Contribution

It introduces a novel experimental approach to identify spinons via spin current measurements, providing theoretical predictions for distinguishing quantum spin liquids.

Findings

Different Mott insulators show distinct spin bias and spin current relations.

Theoretical evaluation of spin current through a Mott insulator-metal interface.

Discussion of experimental parameters for detecting spinons.

Abstract

Existence of spinons is the defining property of quantum spin liquids. These exotic excitations have (fractionalized) spin quantum number and no electric charge, and have been proposed to form Fermi surfaces in the recently discovered organic spin liquid candidates. However direct probes for them are still lacking. In this paper we propose to experimentally identify the spinons by measuring the spin current flowing through the spin liquid candidate materials, which would be a direct test for the existence of spin-carrying mobile excitations. By the nonequilibrium Green function technique we evaluate the spin current through the interface between a Mott insulator and a metal under a spin bias, and find that different kinds of Mott insulators, including quantum spin liquids, can be distinguished by different relations between the spin bias and spin current, In the end we will also discuss relations to experiments and estimate experimentally relevant parameters.