Spin waves excitation at micron-sized, anisotropy modified regions in amorphous Fe80B20 stripes: Local properties and inter-regions coupling

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2021-09, Vol.271, p.115258-1-115258-13, Article 115258
• Main Authors: Urdiroz, Unai, Müller, Cai, Gómez, Alicia, Magaz, M. Teresa, Granados, Daniel, Sánchez Agudo, Marta, Rubio-Zuazo, Juan, Castro, Germán R., Stan, Camelia, Tamura, Nobumichi, Padmore, Howard A., Cebollada, Federico, Palomares, F. Javier, McCord, Jeffrey, González, Jesús M.
• Format: Article
• Language: English
• Subjects: Amorphous Fe80B20; Anisotropy; Anisotropy induction; Aspect ratio; Damping; Decay time; Dispersion relationship; Domain wall stabilization; Group velocity; Magnetic anisotropy; Magnons; MATERIALS SCIENCE; Phase shifters; Phase velocity; Phase-shift; Physics; Propagation distance; Remanence; Spin waves; Synchrotron radiation; Synchrotrons; Wave propagation; X ray irradiation
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2021.115258

[Display omitted] •Dynamic (GHz) characterization of as-prepared strips lithographed from amorphous Fe80B20 films.•Local dynamic (GHz) characterization of micrometric, X-ray irradiated regions (IR)•Damping constant of 3 × 10−3 measured at 5 GHz, 150 Oe dc field in the IR.•Propagation distance of 40 μm measured at 5 GHz, 150 Oe in the IR.•Stabilization (IR) of a 180° wall originates a πphase-shift for spin waves at both sides of the IR. We report on the measurement of the local magnetization dynamics occurring, at units of GHz, in large aspect ratio stripes lithographed from reduced damping amorphous Fe80B20 films. The stripes were submitted to local anisotropy modifications by micrometric beam synchrotron X-ray irradiation. Our results include data on the dispersion relationships and group velocities corresponding to spin waves excited at both the non-irradiated and the irradiated regions. Whereas in the former case we observed standing spin waves with transverse-to-the stripe axis wave vector, in the latter one, for which the wave vector of the spin waves was parallel-to-the stripe axis, propagating spin waves were excited. In both regions, we measured the effective propagation distance of the spin waves, which resulted to be independent of the wave vector orientation. In the spin waves excited at the irradiated region, we also measured the decay time and effective damping coefficient, which was in good agreement with previously reported values obtained from FMR measurements in amorphous Fe80B20 continuous films. We show that the interaction of the non-irradiated and irradiated zones results, at the stripe transverse saturation remanence and under an exciting field frequency of 4 GHz, in the introduction of a π phase shift between the standing spin waves excited at both sides of the irradiated region. This result opens the possibility of using the local, transverse to the stripe axis, magnetic anisotropy easy axis induced by the X-ray irradiation as a crucial constituent of a zero-applied field spin wave phase-shifter.