The effects of spin-spin interactions on magnetoresistance in disordered organic semiconductors

TL;DR

This paper extends a theory of magnetoresistance in disordered organic semiconductors by including spin-spin interactions, revealing angle-dependent effects and new behaviors influenced by dipolar anisotropy.

Contribution

It introduces an analytical framework incorporating exchange and dipolar couplings, advancing understanding of magnetoresistance in disordered organic semiconductors.

Findings

Magnetoresistance depends on the angle of the magnetic field.

New magnetoresistive behaviors are linked to dipolar interaction anisotropy.

Results align with previous experiments and simulations.

Abstract

A recent theory of magnetoresistance in positionally disordered organic semiconductors is extended to include exchange and dipolar couplings between polarons. Analytic results are discovered when the hyperfine, exchange, and dipolar interactions have little time to operate between hopping events. We find an angle-of-field dependence of the magnetoresistance that agrees with previous experiments and numerical simulations. In addition we report new magnetoresistive behavior that critically depends upon the amount of anisotropy in the dipolar interaction.