Pauli spin blockade and the ultrasmall magnetic field effect

TL;DR

This paper presents an analytical model explaining the ultrasmall magnetic field effect and the magnetoconductance line shapes in organic magnetoresistance, emphasizing the role of nuclear fields and hopping rates, aligning with recent experimental and simulation results.

Contribution

It introduces an analytic expression for the polaron-bipolaron transition rate considering nuclear fields, providing new insights into magnetoconductance behaviors in organic materials.

Findings

Qualitative differences in magnetoconductance line shapes explained

Ultrasmall magnetic field effect characterized

Agreement with recent experiments and simulations

Abstract

Based on the spin-blockade model for organic magnetoresistance we present an analytic expression for the polaron-bipolaron transition rate, taking into account the effective nuclear fields on the sites. We reveal the physics producing qualitatively different magnetoconductance line shapes as well as the ultrasmall magnetic field effect, and we study the role of the ratio between the intersite hopping rate and the typical magnitude of the nuclear fields. Our findings are in agreement with recent experiments and numerical simulations.