Non-stationary excitation of two localized spin-wave modes in a nano-contact spin torque oscillator
2013 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, no 15, 153906- p.Article in journal (Refereed) Published
We measure and simulate micromagnetically a framework based upon a nano-contact spin torque oscillator where two distinct localized evanescent spin-wave modes can be detected. The resulting frequency spectrum is composed by two peaks, corresponding to the excited modes, which lie below the ferromagnetic resonance frequency, and a low-frequency tail, which we attribute to the non-stationary switching between these modes. By using Fourier, wavelet, and Hilbert-Huang transforms, we investigate the properties of these modes in time and spatial domains, together with their spatial distribution. The existence of an additional localized mode (which was neither predicted by theory nor by previous numerical and experimental findings) has to be attributed to the large influence of the current-induced Oersted field strength which, in the present setup, is of the same order of magnitude as the external field. As a further consequence, the excited spin-waves, contrarily to what usually assumed, do not possess cylindrical symmetry: the Oersted field induces these modes to be excited at the two opposite sides of the region beneath the nano-contact.
Place, publisher, year, edition, pages
2013. Vol. 114, no 15, 153906- p.
Polarized Current, Hilbert Spectrum, Driven
Other Physics Topics
IdentifiersURN: urn:nbn:se:kth:diva-134737DOI: 10.1063/1.4825065ISI: 000326117900048ScopusID: 2-s2.0-84886547522OAI: oai:DiVA.org:kth-134737DiVA: diva2:669149
FunderSwedish Foundation for Strategic Research Swedish Research CouncilKnut and Alice Wallenberg Foundation
QC 201312032013-12-032013-11-282013-12-03Bibliographically approved