title: Direct-current induced dynamics in Co90 Fe10/Ni80 Fe20 point contacts.
abstract: We have directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current. The precession frequency can be tuned over a range of several gigahertz by varying the applied current. The frequencies of excitation also vary with applied field, resulting in a microwave oscillator that can be tuned from below 5 to above 40 GHz. This novel method of inducing high-frequency dynamics yields oscillations having quality factors from 200 to 800. We compare our results with those from single-domain simulations of current-induced dynamics.
authors.affiliation: National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
authors.forename: W H
authors.initials: WH
authors.lastname: Rippard
authors.forename: M R
authors.initials: MR
authors.lastname: Pufall
authors.forename: S
authors.initials: S
authors.lastname: Kaka
authors.forename: S E
authors.initials: SE
authors.lastname: Russek
authors.forename: T J
authors.initials: TJ
authors.lastname: Silva