title: Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions.
abstract: The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) is the key to developing magnetoresistive random-access-memory (MRAM), magnetic sensors and novel programmable logic devices. Conventional MTJs with an amorphous aluminium oxide tunnel barrier, which have been extensively studied for device applications, exhibit a magnetoresistance ratio up to 70% at room temperature. This low magnetoresistance seriously limits the feasibility of spintronics devices. Here, we report a giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs. The origin of this enormous TMR effect is coherent spin-polarized tunnelling, where the symmetry of electron wave functions plays an important role. Moreover, we observed that their tunnel magnetoresistance oscillates as a function of tunnel barrier thickness, indicating that coherency of wave functions is conserved across the tunnel barrier. The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing gigabit-scale MRAM.
authors.affiliation: NanoElectronics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan. yuasa-s@aist.go.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Yuasa
authors.forename: Taro
authors.initials: T
authors.lastname: Nagahama
authors.forename: Akio
authors.initials: A
authors.lastname: Fukushima
authors.forename: Yoshishige
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Koji
authors.initials: K
authors.lastname: Ando
mesh_terms: D003201:Computers; D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D004566:Electrodes; D004581:Electronics / Q000295:instrumentation*; D004867:Equipment Design; D005240:Feasibility Studies; D016247:Information Storage and Retrieval / Q000379:methods*; D007501:Iron / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D008280:Magnetics / Q000295:instrumentation*; D008420:Manufactured Materials; D008422:Materials Testing; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D013696:Temperature
chemical_list: D008277:Magnesium Oxide; D007501:Iron