Rectification of spin currents in spin chains

TL;DR

This paper investigates how anisotropy and magnetic fields in one-dimensional quantum spin chains can produce rectification effects in spin transport, with potential applications in spintronics.

Contribution

It identifies key ingredients like exchange anisotropy and magnetic fields that enable rectification in both ferromagnetic and antiferromagnetic spin chains, including impurity effects.

Findings

Rectification current requires exchange anisotropy and magnetic field offset.

A bulk anisotropy-induced gap enables measurable rectification.

Magnetic impurities can also induce rectification in antiferromagnetic chains.

Abstract

We study spin transport in nonitinerant one-dimensional quantum spin chains. Motivated by possible applications in spintronics, we consider rectification effects in both ferromagnetic and antiferromagnetic systems. We find that the crucial ingredients in designing a system that displays a nonzero rectification current are an anisotropy in the exchange interaction of the spin chain combined with an offset magnetic field. For both ferromagnetic and antiferromagnetic systems we can exploit the gap in the excitation spectrum that is created by a bulk anisotropy to obtain a measurable rectification effect at realistic magnetic fields. For antiferromagnetic systems we also find that we can achieve a similar effect by introducing a magnetic impurity, obtained by altering two neighboring bonds in the spin Hamiltonian.