SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster Magnetism II
MA 40.49: Poster
Donnerstag, 30. März 2023, 14:00–16:00, P2/EG
Spin-transfer torque ferromagnetic resonance in vortex magnetic tunnel junctions — •Johannes Demir, Karsten Rott, and Günter Reiss — Bielefeld University, Germany
We investigate the gyrotropic mode resonance frequency of the vortex as the free layer of a magnetic tunnel junction (MTJ) by means of spin-transfer torque ferromagnetic resonance (STT-FMR) using a two-port vector network analyzer (VNA). In order to obtain a proper resistance-area (RA) product the capping layer of a commercial wafer was mostly etched down to sputter 8.5 nm permalloy as the vortex layer on top of it afterwards. Subsequently, nanopillars of 300 and 600 nm diameter were fabricated using electron-beam lithography. Using a coplanar-waveguide to feed the GHz-range current through the nanopillar the transmission scattering-parameter S21 was determined. Resonance frequencies of around 240 and 150 MHz for the 300 and 600 nm diameter samples, respectively, were measured in accordance with literature [1]. We recognize a shift of the frequency with increasing the bias voltage indicating a DC-STT contribution.
[1] V. Novosad et al., Phys. Rev. B 72, 024455 (2005)