Current-Induced Magnetization Reversal in High Magnetic Fields inCo/Cu/CoNanopillars

摘要: Angular momentum transfer in magnetic nanostructures mediated by an electric current has become the subject of intense research. Slonscewski and Berger first considered this theoretically 1996 [1,2]. Its experimental observation a few years later [3–7] boosted efforts to understand influence conduction electron spin on magnetization dynamics ferromagnetic presence high currents. A been demonstrated switch direction small element. Reversible changes multilayer resistance have also observed associated with excitations or generation waves. However, in-depth understanding relationship between these two phenomena — reversible irreversible switching magnetization—is still missing. In initial experiments point contact was employed inject densities into [3,6,7]. Subsequent concentrated reduction lateral size Co=Cu=Co trilayers submicron scale, resulting fabrication nanopillar devices [8–14]. point-contact applied field oriented perpendicular thin film plane larger than demagnetization fields (H � 2T ). regime peak structure differential (dV=dI) at critical interpreted as onset induced excitation waves which spin-transfer torque leads uniform precession [3,6,15]. Spin-transfer studies pillar plane. low-field regime, hysteretic jump observed; clear evidence for reversal one layers Hence, effect spin-polarized seemed be quite distinct low regimes. Experimentally, only in-plane devices. Letter we report detailed geometry. For sufficiently large currents polarity is fields. contrast previous results geometry mechanical contacts, cannot understood amplitude magnetization. Micromagnetic modeling suggests that torques induce precessional states evolve static state antiparallel alignment layers.