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Bipolar High Field Excitations in Co/Cu/Co Nanopillars

B. Özyilmaz·A. D. Kent·M. J. Rooks·J. Z. Sun
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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.

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B. Özyilmaz, A. D. Kent, M. J. Rooks, J. Z. Sun. 2004-07-08. Bipolar High Field Excitations in Co/Cu/Co Nanopillars. https://doi.org/10.1103/physrevb.71.140403

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