Time-resolved X-ray microscopy is used to image the influence of alternating high-density currents on the magnetization dynamics of ferromagnetic vortices. Spin-torque induced vortex gyration is observed in micrometer-sized permalloy squares. The phases of the gyration in structures with different chirality are compared to an analytical model and micromagnetic simulations, considering both alternating spinpolarized currents and the current's Oersted field. In our case the driving force due to spin-transfer torque is about 70% of the total excitation while the remainder originates from the current's Oersted field. This finding has implications to magnetic storage devices using spin-torque driven magnetization switching and domain-wall motion.
@article{arxiv.0801.4719,
title = {Time-Resolved X-ray Microscopy of Spin-Torque-Induced Magnetic Vortex Gyration},
author = {Markus Bolte and Guido Meier and Benjamin Krueger and Andre Drews and Rene Eiselt and Lars Bocklage and Stellan Bohlens and Tolek Tyliszczak and Arne Vansteenkiste and Bartel Van Waeyenberge and Kang Wei Chou and Aleksandar Puzic and Hermann Stoll},
journal= {arXiv preprint arXiv:0801.4719},
year = {2009}
}