Spin Wave Excitations and Winter’s Magnons in Vertically Coupled Vortex State Permalloy Dots

Autor: Vitali V. Metlushko, Konstantin Y. Guslienko, Antonio Lara, Farkhad G. Aliev, M. García Hernández, A. A. Awad
Přispěvatelé: Ministerio de Ciencia e Innovación (España), Ministerio de Economía y Competitividad (España), Comunidad de Madrid, Ikerbasque Basque Foundation for Science
Rok vydání: 2012
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1557-1947
1557-1939
Popis: Circular soft magnetic dots are the main elements of many proposed novel spintronics devices, capable of fascinating spin-based electronics applications, from extremely sensitive magnetic field sensors, to current-tunable microwave vortex oscillators. Here, we investigate static and broadband dynamic magnetization responses of vertically coupled Permalloy (Py) magnetic dots in the vortex state in layered nanopillars (experiment and simulations), which were explored as a function of in-plane magnetic field and interlayer separation. Under reduction of magnetic field from saturation for the field range just above vortexvortex ground state. We observe a metastable double vortex state for each of the dots. In this state, novel kinds of spin waves (Winter’s magnons along domain walls between vortex cores and half-edge antivortex) are excited. For dipolarly coupled circular Py(25 nm)/Cu(20 nm)/Py(25 nm) trilayer nanopilars of diameter 600 nm, a small in-plane field splits the eigenfrequencies of azimuthal spin wave modes inducing an abrupt transition between acoustic (in-phase) and optic (out-of-phase) kinds of the low-lying coupled spin wave modes. Qualitatively similar changes (although more gradual and at higher values of in-plane fields) occur in the exchange coupled Py(25 nm)/Cu(1 nm)/Py(25 nm) trilayer nanopillars. These findings are in qualitative agreement with micromagnetic dynamic simulations.
The authors acknowledge support from Spanish MINECO (MAT2012-32743; MAT2009-10139) and CM (P2009/MAT-1726). K.G. acknowledges support by IKERBASQUE and partial support by MEC Grants PIB2010US-00153 and FIS2010-20979-C02-01.
Databáze: OpenAIRE
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