Through detailed experimental studies of the angular dependence of spin wave excitations in nanocontact-based spin-torque oscillators, we demonstrate that two distinct spin wave modes can be excited, with different frequency, threshold currents and frequency tuneability. Using analytical theory and micromagnetic simulations we identify one mode as an exchange-dominated propagating spin wave, and the other as a self-localized nonlinear spin wave bullet. Wavelet-based analysis of the simulations indicates that the apparent simultaneous excitation of both modes results from rapid mode hopping induced by the Oersted field.
@article{arxiv.0909.3331,
title = {Experimental evidence of self-localized and propagating spin wave modes in obliquely magnetized current-driven nanocontacts},
author = {Stefano Bonetti and Vasyl S. Tiberkevich and Giancarlo Consolo and Giovanni Finocchio and Pranaba Muduli and Fred Mancoff and Andrei N. Slavin and Johan Åkerman},
journal= {arXiv preprint arXiv:0909.3331},
year = {2011}
}