Bipolar High Field Excitations in Co/Cu/Co Nanopillars

Abstract

Current-induced magnetic excitations in Co/Cu/Co bilayer nanopillars ($\sim$50 nm in diameter) 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 longitudinal 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.

4 pages, 4 figures+ 2 additional jpg figures (Fig. 2d and Fig. 3) high resolution figures and recent related articles are available at: http://www.physics.nyu.edu/kentlab/news.html

References in corpus (3)

• Current-Induced Nanomagnet Dynamics for Magnetic Fields Perpendicular to the Sample Plane
• Current Induced Excitations in Cu/Co/Cu Single Ferromagnetic Layer Nanopillars
• Current-Induced Effective Magnetic Fields in Co/Cu/Co Nanopillars

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• Current induced transverse spin-wave instability in thin ferromagnets: beyond linear stability analysis
• Nanofabrication of spin-transfer torque devices by a PMMA mask one step process: GMR versus single layer devices
• Thermal Dynamics in Symmetric Magnetic Nanopillars Driven by Spin Transfer
• Spin-transfer-induced excitations in bilayer magnetic nanopillars at high fields: The effects of contact layers