Spin-Transfer Torques in Single-Crystalline Nanopillars
| Autor: | A. van der Hart, R. Lehndorff, H. Dassow, Daniel E. Bürgler, Claus M. Schneider |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Advances in Solid State Physics ISBN: 9783540382348 ResearcherID |
| DOI: | 10.1007/978-3-540-38235-5_10 |
| Popis: | Current-induced magnetization switching (CIMS) due to spin-transfer torques is an advanced switching concept for magnetic nanostructures in spintronic devices. Most previous studies employed sputtered, polycrystalline samples. Here, we report on the first measurements of CIMS in single-crystalline nanopillars. Fe(14 nm)/Cr(0.9 nm)/Fe(10 nm)/Ag(6 nm)/Fe(2 nm) multilayers are deposited by molecular beam epitaxy. The central Fe layer is coupled to the 14 nm-thick Fe layer by interlayer exchange coupling over Cr, and the topmost Fe layer is decoupled (free layer). The maximum observed giant magnetoresistance with current perpendicular to the layers (CPP-GMR) is 2.6% at room temperature and up to 5.6% at 4 K. Nanopillars with a diameter of 150nm are prepared by optical and e-beam lithography. The opposite scattering spin asymmetries of Fe/Cr and Fe/Ag interfaces enable us to observe CIMS at small magnetic fields and opposite current polarity in a single device. The critical current density for switching is j c ≈ 108 A/cm2. At high magnetic fields, step-like resistance changes are measured at positive currents and are attributed to current-driven magnetic excitations. |
| Databáze: | OpenAIRE |
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