Probing excitations in insulators via injection of spin-currents

TL;DR

This paper introduces a spin transport experiment to probe low-energy excitations in insulators, providing a formalism to analyze spin-current transfer and distinguish magnetic ground states.

Contribution

It develops a general formalism for calculating spin-current injection from metals to insulators, enabling detection of magnetic and non-magnetic ground states.

Findings

Identifies features in spin-conductance for different insulator states

Provides a method to detect ground state magnetic order

Enhances understanding of spin transport in insulators

Abstract

We propose a spin transport experiment to measure the low-energy excitations in insulators with spin degrees of freedom, with a focus on detecting ground states that lack magnetic order. A general formalism to compute the spin-current from a metal with a non-equilibrium distribution of spins to an insulator is developed. It is applied to insulating states with and without long range magnetic order, and salient features in the spin-conductance are noted.