Spin injection and spin transport in paramagnetic insulators

TL;DR

This paper studies how spin injection and transport behave in paramagnetic insulators using theoretical models, revealing temperature-dependent effects crucial for spintronics device optimization.

Contribution

It provides a theoretical analysis of spin injection and transport in paramagnetic insulators across different temperature regimes, highlighting their implications for spintronics.

Findings

Spin injection is insensitive to temperature above the magnetic transition.

Spin conductance peaks near the magnetic transition temperature.

Conductance drops to zero at zero temperature.

Abstract

We investigate the spin injection and the spin transport in paramagnetic insulators described by simple Heisenberg interactions using auxiliary particle methods. Some of these methods allow access to both paramagnetic states above magnetic transition temperatures and magnetic states at low temperatures. It is predicted that the spin injection at an interface with a normal metal is rather insensitive to temperatures above the magnetic transition temperature. On the other hand below the transition temperature, it decreases monotonically and disappears at zero temperature. We also analyze the bulk spin conductance. It is shown that the conductance becomes zero at zero temperature as predicted by linear spin wave theory but increases with temperature and is maximized around the magnetic transition temperature. These findings suggest that the compromise between the two effects determines the optimal temperature for spintronics applications utilizing magnetic insulators.