Frequency dependent transport through a spin chain

TL;DR

This paper investigates frequency-dependent spin transport in a nonitinerant one-dimensional spin chain with impurities, revealing a capacitor-like behavior for spin and how transport varies with frequency, anisotropy, and magnetic field.

Contribution

It introduces a model of a spin chain with impurities acting as a spin capacitor and analyzes its frequency-dependent transport properties, including a measurement method.

Findings

Impurities flow to strong coupling at low energy, effectively segmenting the chain.

Finite frequency spin transport increases with frequency.

Transport characteristics depend on anisotropy and magnetic field.

Abstract

Motivated by potential applications in spintronics, we study frequency dependent spin transport in nonitinerant one-dimensional spin chains. We propose a system that behaves as a capacitor for the spin degree of freedom. It consists of a spin chain with two impurities a distance $d$ apart. We find that at low energy (frequency) the impurities flow to strong coupling, thereby effectively cutting the chain into three parts, with the middle island containing a discrete number of spin excitations. At finite frequency spin transport through the system increases. We find a strong dependence of the finite frequency characteristics both on the anisotropy of the spin chain and the applied magnetic field. We propose a method to measure the finite-frequency conductance in this system.