title: Substantial reduction of critical current for magnetization switching in an exchange-biased spin valve.
abstract: Great interest in current-induced magnetic excitation and switching in a magnetic nanopillar has been caused by the theoretical predictions of these phenomena. The concept of using a spin-polarized current to switch the magnetization orientation of a magnetic layer provides a possible way to realize future 'current-driven' devices: in such devices, direct switching of the magnetic memory bits would be produced by a local current application, instead of by a magnetic field generated by attached wires. Until now, all the reported work on current-induced magnetization switching has been concentrated on a simple ferromagnet/Cu/ferromagnet trilayer. Here we report the observation of current-induced magnetization switching in exchange-biased spin valves (ESPVs) at room temperature. The ESPVs clearly show current-induced magnetization switching behaviour under a sweeping direct current with a very high density. We show that insertion of a ruthenium layer between an ESPV nanopillar and the top electrode effectively decreases the critical current density from about 10(8) to 10(7) A cm(-2). In a well-designed 'antisymmetric' ESPV structure, this critical current density can be further reduced to 2 x 10(6) A cm(-2). We believe that the substantial reduction of critical current could make it possible for current-induced magnetization switching to be directly applied in spintronic devices, such as magnetic random-access memory.
authors.affiliation: Department of Materials Science, Graduate School of Engineering, Tohoku University, and CREST, Japan Science and Technology Agency, Sendai 980-8579, Japan. yjiang@material.tohoku.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Jiang
authors.forename: T
authors.initials: T
authors.lastname: Nozaki
authors.forename: S
authors.initials: S
authors.lastname: Abe
authors.forename: T
authors.initials: T
authors.lastname: Ochiai
authors.forename: A
authors.initials: A
authors.lastname: Hirohata
authors.forename: N
authors.initials: N
authors.lastname: Tezuka
authors.forename: K
authors.initials: K
authors.lastname: Inomata