We study current-driven magnetization switching in nanofabricated Ni84Fe16/Cu/Ni84Fe16 trilayers at 295 K and 4.2 K. The shape of the hysteretic switching diagram at low magnetic field changes from 295 K to 4.2 K. The reversible behavior at higher field involves two phenomena, a threshold current for magnetic excitations closely correlated with the switching current, and a peak in differential resistance characterized by telegraph noise, with average period that decreases exponentially with current and shifts with temperature. We interpret both static and dynamic results at 295 K and 4.2 K in terms of thermal activation over a potential barrier, with a current dependent effective magnetic temperature.
@article{arxiv.cond-mat/0303149,
title = {Current-Driven Magnetic Excitations in Permalloy-Based Multilayer Nanopillars},
author = {S. Urazhdin and Norman O. Birge and W. P. Pratt and J. Bass},
journal= {arXiv preprint arXiv:cond-mat/0303149},
year = {2009}
}