Excitation of magnons or spin-waves driven by nominally unpolarized transport currents in point contacts of normal and ferromagnetic metals is probed by irradiating the contacts with microwaves. Two characteristic dynamic effects are observed: a rectification of off-resonance microwave current by spin-wave nonlinearities in the point contact conductance, and a resonant stimulation of spin-wave modes in the nano-contact core by the microwave field. These observations provide a direct evidence that the magnetoconductance effects observed are due to GHz spin dynamics at the ferromagnetic interface driven by the spin transfer torque effect of the transport current.
@article{arxiv.0806.3805,
title = {Spin dynamics in point contacts to single ferromagnetic films},
author = {O. P. Balkashin and V. V. Fisun and I. K. Yanson and L. Yu. Triputen and A. Konovalenko and V. Korenivski},
journal= {arXiv preprint arXiv:0806.3805},
year = {2009}
}