Tunneling magnetoresistance in epitaxial discontinuous Fe/MgO multilayers

Abstract

3 páginas, 3 figuras.-- et al. ; Epitaxial discontinuous Fe/MgO multilayers have been grown by pulsed laser deposition on MgO(001) single-crystal substrates. The multilayers with 0.6 nm nominal Fe layers thickness are superparamagnetic and demonstrate tunneling magnetoresistance (TMR) in the current-in-plane configuration. Increasing deposition temperature causes an improvement in crystal quality and is accompanied by higher TMR ratios. The maximum value (9.2% TMR at room temperature and 18 kOe magnetic field) trebles that of polycrystalline samples deposited simultaneously on glass substrates. A model formula for TMR ratio that includes both spin-dependent tunneling and spin-filtering effect is proposed to explain these results. ; Financial support by Spanish Ministry of Science (through project No. MAT2008-06567-C02 including FEDER funding) and by the Aragón Regional Government (through projects E26 and PI059/08) is acknowledged. Work of A.V. and G.N.K. was supported by Portuguese FCT through "Ciencia 2008" and "Ciencia 2007" programs, respectively. ; Peer reviewed