title: Tunable short-wavelength spin wave excitation from pinned magnetic domain walls.
abstract: Miniaturization of magnonic devices for wave-like computing requires emission of short-wavelength spin waves, a key feature that cannot be achieved with microwave antennas. In this paper, we propose a tunable source of short-wavelength spin waves based on highly localized and strongly pinned magnetic domain walls in ferroelectric-ferromagnetic bilayers. When driven into oscillation by a microwave spin-polarized current, the magnetic domain walls emit spin waves with the same frequency as the excitation current. The amplitude of the emitted spin waves and the range of attainable excitation frequencies depend on the availability of domain wall resonance modes. In this respect, pinned domain walls in magnetic nanowires are particularly attractive. In this geometry, spin wave confinement perpendicular to the nanowire axis produces a multitude of domain wall resonances enabling efficient spin wave emission at frequencies up to 100 GHz and wavelengths down to 20 nm. At high frequency, the emission of spin waves in magnetic nanowires becomes monochromatic. Moreover, pinning of magnetic domain wall oscillators onto the same ferroelectric domain boundary in parallel nanowires guarantees good coherency between spin wave sources, which opens perspectives towards the realization of Mach-Zehnder type logic devices and sensors.
authors.affiliation: Department of Electrical Energy, Systems and Automation, Ghent University, Technologiepark 913, B-9052 Ghent, Belgium.
authors.forename: Ben
authors.initials: B
authors.lastname: Van de Wiele
authors.affiliation: NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Sampo J
authors.initials: SJ
authors.lastname: Hämäläinen
authors.affiliation: Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Prague, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Baláž
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Ferrara, Via Saragat 1, 44122 Ferrara, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Montoncello
authors.affiliation: NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland.
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: van Dijken