Mode-coupling mechanisms in nanocontact spin-torque oscillators
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 10, 104405Article in journal (Refereed) Published
Spin-torque oscillators (STOs) are devices that allow for the excitation of a variety of magnetodynamical modes at the nanoscale. Depending on both external conditions and intrinsic magnetic properties, STOs can exhibit regimes of mode hopping and even mode coexistence. Whereas mode hopping has been extensively studied in STOs patterned as nanopillars, coexistence has been only recently observed for localized modes in nanocontact STOs (NC-STOs), where the current is confined to flow through a NC fabricated on an extended pseudo spin valve. By means of electrical characterization and a multimode STO theory, we investigate the physical origin of the mode-couplingmechanisms favoring coexistence. Two couplingmechanisms are identified: (i) magnon-mediated scattering and (ii) intermode interactions. These mechanisms can be physically disentangled by fabricating devices where the NCs have an elliptical cross section. The generation power and linewidth from such devices are found to be in good qualitative agreement with the theoretical predictions, as well as provide evidence of the dominant mode-coupling mechanisms.
Place, publisher, year, edition, pages
2015. Vol. 91, no 10, 104405
IdentifiersURN: urn:nbn:se:kth:diva-163971DOI: 10.1103/PhysRevB.91.104405ISI: 000350957800001ScopusID: 2-s2.0-84961343781OAI: oai:DiVA.org:kth-163971DiVA: diva2:810595
FunderKnut and Alice Wallenberg FoundationSwedish Foundation for Strategic Research Swedish Research Council
QC 201505072015-05-072015-04-132015-05-07Bibliographically approved