Spin-transfer switching and low-field precession in exchange-biased spin   valve nano-pillars
  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. 
M. C. Wu, A. Aziz, D. Morecroft, M. G. Blamire, M. C. Hickey, M. Ali,   G. Burnell and B.J. Hickey