Oxygen-vacancy driven tunnelling spintronics across MgO

U. Halisdemir, F. Schleicher, D. J. Kim, B. Taudul, D. Lacour, W. S. Choi, M. Gallart, S. Boukari, G. Schmerber, V. Davesne, P. Panissod, D. Halley, H. Majjad, Y. Henry, B. Leconte, A. Boulard, D. Spor, N. Beyer, C. Kieber, E. SternitzkyO. Cregut, M. Ziegler, F. Montaigne, J. Arabski, E. Beaurepaire, W. Jo, M. Alouani, P. Gilliot, M. Hehn, M. Bowen

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

4 Scopus citations

Abstract

The conservation of an electron's spin and symmetry as it undergoes solid-state tunnelling within magnetic tunnel junctions (MTJs) is thought to be best understood using MgO-based MTJs1. Yet the very large experimental values of tunnelling magnetoresistance (TMR) that justify this perception are often associated with tunnelling barrier heights well below those suggested by the MgO optical band gap. This combination of high TMR and low RA-product, while spawning spin-transfer/spin-orbit torque experiments and considerable industrial interest, cannot be explained by standard theory. Noting the impact of a tunnel barrier's altered stoichiometry on TMR2, we reconcile this 10+year-old contradiction between theory and experiment by considering the impact of the MgO barrier's structural defects3-5. We find that the ground and excited states of oxygen vacancies can promote localized states within the band gap with differing electronic character. By setting symmetry- and temperature-dependent tunnelling barrier heights, they alter symmetry-polarized tunnelling and thus TMR. We will examine how annealing, depending on MgO growth conditions, can alter the nature of these localized states. This oxygen vacancy paradigm of inorganic tunnelling spintronics opens interesting perspectives into endowing the MTJ with additional functionalities, such as optically manipulating the MTJ's spintronic response.

Original languageEnglish
Title of host publicationSpintronics IX
EditorsJean-Eric Wegrowe, Henri-Jean Drouhin, Manijeh Razeghi
PublisherSPIE
ISBN (Electronic)9781510602533
DOIs
StatePublished - 2016
EventSpintronics IX - San Diego, United States
Duration: 28 Aug 20161 Sep 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume9931
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceSpintronics IX
Country/TerritoryUnited States
CitySan Diego
Period28/08/161/09/16

Bibliographical note

Funding Information:
F.S. gratefully acknowledges financial support from the CNRS. We thank Y. Yin for assistance with optical experiments and S. Colis for technical assistance, the STNano technological platform for access and J. Stoll, J.-G. Faullumel, B. Muller and G. Dekyndt of the IPCMS machine shop for assistance. This work was supported by grants from the EU (EC FP6 NMP3-CT-2006-033370), the ANR (ANR-06-NANO-033-01, ANR-09-JCJC-0137, ANR-14-CE26-0009-01 and ANR-09-Blan-076), the Labex NIE (ANR-11-LABX-0058-NIE 'Symmix'), the CNRS (STII PEPS 'SpinTrans', PICS 'Oxyspin'), the University of Strasbourg, La Région Alsace, le FEDER and La Région Lorraine; and by the Korean MEST Grant No. 2010K000339 from CNMT under 21st Century Frontier R&D Programs; Grant No. NRF 2010- 0020416.

Publisher Copyright:
© 2016 SPIE.

Keywords

  • Localized states
  • Magnetic tunnel junction
  • Oxygen vacancy
  • Photoluminescence
  • Spin transfer torque
  • Spintronics

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