Bipolar high-field excitations in Co/Cu/Co nanopillars
نویسندگان
چکیده
Current-induced magnetic excitations in Co/Cu/Co bilayer nanopillars s,50 nm in diameterd have been studied experimentally at low temperatures for large applied fields perpendicular to the layers. At sufficiently high current densities excitations, which lead to a decrease in differential resistance, are observed for both current polarities. Such bipolar excitations are not expected in a single domain model of spin transfer. We propose that at high current densities strong asymmetries in the spin accumulation cause spin-wave instabilities transverse to the current direction in bilayer samples, similar to those we have reported for single magnetic layer junctions.
منابع مشابه
Current-driven excitations in symmetric magnetic nanopillars.
We study experimentally the current-driven magnetic excitations in symmetric Co/Cu/Co nanopillars. In contrast with all the previous observations where the current of only one polarity is capable of exciting a multilayer system saturated by an externally applied magnetic field, we observe that both polarities of the applied current trigger excitations in a symmetric multilayer. This may indicat...
متن کاملCurrent-induced excitations in single cobalt ferromagnetic layer nanopillars.
Current-induced excitations in Cu/Co/Cu single ferromagnetic layer nanopillars ( approximately 50 nm in diameter) have been studied experimentally as a function of Co layer thickness at low temperatures for large applied fields perpendicular to the layers. For asymmetric junctions current-induced excitations are observed at high current densities for only one polarity of the current and are abs...
متن کاملCurrent-induced magnetization reversal in high magnetic fields in Co/Cu/Co nanopillars.
Current-induced magnetization dynamics in Co/Cu/Co trilayer nanopillars (approximately 100 nm in diameter) have been studied experimentally at low temperatures for large applied fields perpendicular to the layers. At 4.2 K an abrupt and hysteretic increase in resistance is observed at high current densities for one polarity of the current, comparable to the giant magnetoresistance effect observ...
متن کاملSpin transfer in bilayer magnetic nanopillars at high fields as a function of free-layer thickness
Spin transfer in asymmetric Co-Cu-Co bilayer magnetic nanopillars junctions has been studied at low temperature as a function of free-layer thickness. The phase diagram for current-induced magnetic excitations has been determined for magnetic fields up to 7.5 T applied perpendicular to the junction surface and freelayers thicknesses from 2 to 5 nm. The junction magnetoresistance is independent ...
متن کاملCurrent-induced effective magnetic fields in Co/Cu/Co nanopillars
We present a method to measure the effective field contribution to spin-transfer-induced interactions between the magnetic layers in a bilayer nanostructure, which enables spin current effects to be distinguished from the usual charge-current-induced magnetic fields. This technique is demonstrated on submicron Co/Cu/Co nanopillars. The hysteresis loop of one of the magnetic layers in the bilaye...
متن کامل