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Direct-Current Induced Dynamics in Co90Fe10/Ni80Fe20 Point Contacts



William H. Rippard, Matthew R. Pufall, Shehzaad F. Kaka, Stephen E. Russek, Thomas J. Silva


We have directly measured coherent high-frequency magnetization dynamics in ferromagnetic films induced by a spin-polarized dc current. The precision 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 oscillation having quality factors from 200 to 800. We compare our results with those from single-domain simulation of current induced dynamics.
Physical Review Letters


magnetization dynamics, point contacts, rf excitations, spin transfer
Created January 16, 2004, Updated February 19, 2017