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Current-Induced Effective Magnetic Fields in Co/Cu/Co Nanopillars

M. A. Zimmler·B. Özyilmaz·W. Chen·A. D. Kent·J. Z. Sun·M. J. Rooks·R. H. Koch
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Abstract

We present a method to measure the effective field contribution to spin-transfer-induced interactions between the magnetic layers in a trilayer 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 trilayer is measured as a function of current while the direction of magnetization of the other layer is kept fixed, first in one direction and then in the opposite direction. These measurements show a current-dependent shift of the hysteresis loop which, based on the symmetry of the magnetic response, we associate with spin-transfer. The observed loop-shift with applied current at room temperature is reduced in measurements at 4.2 K. We interprete these results both in terms of a spin-current dependent effective activation barrier for magnetization reversal and a spin-current dependent effective magnetic field. From data at 4.2 K we estimate the magnitude of the spin-transfer induced effective field to be $\sim 1.5 \times 10^{-7} $ Oe cm$^2$/A, about a factor of 5 less than the spin-transfer torque.

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M. A. Zimmler, B. Özyilmaz, W. Chen, A. D. Kent, J. Z. Sun, M. J. Rooks, R. H. Koch. 2004-05-26. Current-Induced Effective Magnetic Fields in Co/Cu/Co Nanopillars. https://doi.org/10.1103/physrevb.70.184438

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