MgO magnetic tunnel junctions of enduring F-type upon annealing. (2nd October 2015)

• Record Type: Journal Article
• Authors: Schleicher, F; Halisdemir, U; Urbain, E; Lacour, D; Gallart, M; Boukari, S; Montaigne, F; Beaurepaire, E; Gilliot, P; Hehn, M; Bowen, M
• Is Part Of: Journal of physics. Volume 48:Number 43(2015)
• Publication Date: 2015-10-02
• Subjects: spintronics -- oxygen vacancies -- tunnelling magnetoresistance; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/43/435004
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: The authors performed magnetotransport experiments to determine whether annealing alters the oxygen vacancy-mediated tunnelling potential landscape of the central portion of a MgO ultrathin film within sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions. Using the Î rel method reveals a temperature-dependent tunnelling barrier height for a non-annealed barrier that arises from single oxygen vacancies (F centres) and is qualitatively identical to that found for its partly and fully annealed counterparts. Thus these MTJs with F centres remain of F-type upon annealing. This explicitly confirms that the large tunnel-magnetoresistance (TMR) increase upon annealing results mainly from structural modifications of MgO and CoFeB and not from vacancy pairing within the barrier. Photoluminescence spectra performed on both annealed and non-annealed thin MgO films grown on CoFeB electrodes support this conclusion. This work should promote renewed scrutiny over the precise impact of annealing on tunnelling magnetotransport across MgO.