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 ∼1.5×10−7 Oe cm2/A, about a factor of 5 less than the spin-transfer torque.
@article{arxiv.cond-mat/0405617,
title = {Current-Induced Effective Magnetic Fields in Co/Cu/Co Nanopillars},
author = {M. A. Zimmler and B. Özyilmaz and W. Chen and A. D. Kent and J. Z. Sun and M. J. Rooks and R. H. Koch},
journal= {arXiv preprint arXiv:cond-mat/0405617},
year = {2016}
}