Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

In the field of magnonics, spin waves are envisioned as a new candidate for information transport and processing. Since spin waves propagate without any charge displacement and are free from Joule heating, they offer significant reduction of energy consumption in devices. The spin transfer torque (STT) effect originating from conduction electrons is a powerful method for modulating spin waves. Here, we investigated the current induced Doppler shift of backward volume spin waves.
We fabricated a NiFe stripe with a width of 2 µm, which was magnetized in backward volume configuration. The antennas fabricated on top of the NiFe stripe were connected to a vector network analyzer for measuring the spin-wave spectra. We applied a dc current to the NiFe stripe. For a current density of 5 × 10^10 A/m^2 the spin-wave frequencies shifted +170 MHz compared to the spin-wave spectra without dc current. This frequency shift is 60 times larger than previous works reported for forward volume spin waves. Hence, we demonstrated giant frequency modulation of backward volume spin waves by a dc current.