Oxygen impurities link bistability and magnetoresistance in organic spin valves

Bergenti, I. et al. (2018) Oxygen impurities link bistability and magnetoresistance in organic spin valves. ACS Applied Materials and Interfaces, 10(9), pp. 8132-8140. (doi:10.1021/acsami.7b16068) (PMID:29411962)

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Abstract

Vertical cross-bar devices based on manganite and cobalt injecting electrodes and metal-quinoline molecular transport layer are known to manifest both magnetoresistance and electrical bistability. The two effects are strongly interwoven, inspiring new device applications such as electrical control of the magnetoresistance and magnetic modulation of bistability. To investigate the full device functionality, we first identify the mechanism responsible for electrical switching by associating the electrical conductivity and the impedance behavior with chemical states of buried layers obtained by in operando photoelectron spectroscopy. These measurements revealed that a significant fraction of oxygen ions migrates under voltage polarity, resulting in a modification of the electronic properties of the organic material and of the oxidation of interfacial layer with ferromagnetic contacts. Variable oxygen doping of the organic molecule represents the key element for correlating bistability and magnetoresistance and our measurements provide the first experimental evidence in favor of the impurity band model describing the spin transport in organic semiconductors in similar devices.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:MacLaren, Dr Donald
Authors: Bergenti, I., Borgatti, F., Calbucci, M., Riminucci, A., Cecchini, R., Graziosi, P., MacLaren, D. A., Giglia, A., Rueff, J. P., Céolin, D., Pasquali, L., and Dediu, V.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:ACS Applied Materials and Interfaces
Publisher:American Chemical Society
ISSN:1944-8244
ISSN (Online):1944-8252
Published Online:07 February 2018
Copyright Holders:Copyright © 2018 American Chemical Society
First Published:First published in ACS Applied Materials and Interfaces 10(9):8132-8140
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
530721Integrating advanced nanomaterials into transformative technologiesDonald MaclarenEngineering and Physical Sciences Research Council (EPSRC)EP/I00419X/1P&A - PHYSICS & ASTRONOMY