Conductance switching, hysteresis, and magnetoresistance in organic semiconductors

TL;DR

This paper theoretically investigates charge transport in organic spin-valves, revealing hysteretic conductance switching due to polarons and an exponential bias dependence of magnetoresistance, with implications for device applications.

Contribution

It introduces a model combining the Su-Schrieffer-Heeger framework with NEGF to explain conductance hysteresis and magnetoresistance in organic semiconductors.

Findings

Polaron formation causes hysteretic conductance switching.

Magnetoresistance exhibits exponential bias dependence.

Results align with experimental observations and potential device uses.

Abstract

The controllability of charge transport through an organic molecular spin-valve system is theoretically investigated on the basis of a Su-Schrieffer-Heeger model combined with the non-equilibrium Green's function formalism. We show how the formation of polaron in the organic sub-structure leads to a hysteretic conductance switching, via sweeping either the bias voltage or the electrochemical potential. We further obtain an exponential dependence of the magnetoresistance as a function of the applied bias voltage. The implications of calculated results in relation to experiments and device applications are addressed and commented.