Spin transport and bipolaron density in organic polymers

TL;DR

This paper develops a theoretical model for spin-polarized charge transport in organic polymers, revealing how bipolaron density varies with magnetization angle, offering a new method to probe spin accumulation.

Contribution

It introduces a diffusive transport theory incorporating polaron-bipolaron conversion and predicts angle-dependent bipolaron density in organic polymers.

Findings

Bipolaron density depends on the magnetization angle theta.

The model demonstrates a novel way to probe spin accumulation.

Bipolarons, despite being spinless, influence spin transport properties.

Abstract

We present a theory for spin-polarized transport through a generic organic polymer connected to ferromagnetic leads with arbitrary angle theta between their magnetization directions, taking into account the polaron and bipolaron states as effective charge and spin carriers. Within a diffusive description of polaron-bipolaron transport including polaron-bipolaron conversion, we find that the bipolaron density depends on the angle theta. This is remarkable, given the fact that bipolarons are spinless quasiparticles, and opens a new way to probe spin accumulation in organic polymers.