Controlling magnetoresistance by oxygen impurities in Mq3-based molecular spin valves

TL;DR

This paper investigates how oxygen impurities influence magnetoresistance in organic spin valves, revealing that oxygen migration and carrier concentration critically affect device performance, with implications for controlling spin transport.

Contribution

It demonstrates that oxygen migration and impurity bands are key to understanding and controlling MR in molecular spin valves, a novel insight into device behavior.

Findings

MR correlates with resistance due to impurity band effects

Oxygen migration modulates charge carrier concentration

Interface oxygen migration controls device response

Abstract

The understanding of magnetoresistance (MR) in organic spin valves (OSVs) based on molecular semiconductors is still incomplete after its demonstration more than a decade ago. While carrier concentration may play an essential role in spin transport in these devices, direct experimental evidence of its importance is lacking. We probed the role of charge carrier concentration by studying the interplay between MR and multilevel resistive switching in OSVs. The present work demonstrates that all salient features of these devices, particularly the intimate correlation between MR and resistance, can be accounted for by the impurity band model, based on oxygen migration. Finally, we highlight the critical importance of carrier concentration in determining spin transport and MR in OSVs and the role of interface-mediated oxygen migration in controlling the OSVs response.