Using a three-dimensional focused-ion beam lithography process we have fabricated nanopillar devices which show spin transfer torque switching at zero external magnetic fields. Under a small in-plane external bias field, a field-dependent peak in the differential resistance versus current is observed similar to that reported in asymmetrical nanopillar devices. This is interpreted as evidence for the low-field excitation of spin waves which in our case is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange bias layer coupled to a relatively thin CoFe fixed layer.
@article{arxiv.0802.1003,
title = {Spin-transfer switching and low-field precession in exchange-biased spin valve nano-pillars},
author = {M. C. Wu and A. Aziz and D. Morecroft and M. G. Blamire and M. C. Hickey and M. Ali and G. Burnell and B. J. Hickey},
journal= {arXiv preprint arXiv:0802.1003},
year = {2009}
}