Sub-micrometer near-field focusing of spin waves in ultrathin YIG films

• Published in: Applied physics letters Vol. 116; no. 6
• Main Authors: Divinskiy, B., Thiery, N., Vila, L., Klein, O., Beaulieu, N., Ben Youssef, J., Demokritov, S. O., Demidov, V. E.
• Format: Journal Article
• Language: English
• Published: American Institute of Physics 10-02-2020
• Subjects: Condensed Matter; Physics
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5131689

We experimentally demonstrate tight focusing of a spin wave beam excited in extended
nanometer-thick films of yttrium iron garnet by a simple microscopic antenna functioning
as a single-slit near-field lens. We show that the focal distance and the minimum
transverse width of the focal spot can be controlled in a broad range by varying the
frequency/wavelength of spin waves and the antenna geometry. The experimental data are in
good agreement with the results of numerical simulations. Our findings provide a simple
solution for the implementation of magnonic nanodevices requiring a local concentration of
the spin-wave energy.