[show abstract][hide abstract] ABSTRACT: We report on the propagation of spin waves in permalloy microstripes. By means of scanning Kerr microscopy combined with continuous microwave excitation, we detect the time evolution of spin-wave interference patterns in an external magnetic field. Assuming transverse spin-wave quantization we can directly measure the amplitude, phase velocity and damping for the corresponding transversal wave mode numbers m. We find that the spin-wave interference pattern is dominated by m=0 and m=2 with phase velocities v_0=71 km/s and v_2=47 km/s, respectively. Comment: 3 pages, 3 figures, submitted to Applied Physics Letters
[show abstract][hide abstract] ABSTRACT: Broadband spin-wave spectroscopy is performed on two arrays of long 300- nm -wide Ni <sub>20</sub> Fe <sub>80</sub> wires which exhibit two different edge-to-edge separations a of 700 and 200 nm . When the in-plane field H⃗ is applied a few degrees off from the hard axis direction, an intermediate field regime is found where the central region and the edges of a wire are magnetized in different directions. Here, resonances are pronounced and reflect spin waves confined on the sub- 100 nm scale within a wire. For small a , the confinement effect is found to occur over a broad regime of H . These results are relevant for high-density integration of magnonic waveguides.
[show abstract][hide abstract] ABSTRACT: We investigate the spin-wave dispersion in rolled-up Permalloy microtubes based on self-rolling strained semiconductor layers. Using microwave absorption spectroscopy we find that these structures exhibit a characteristic spin-wave mode spectrum. The magnetization and spin-wave resonance at zero external magnetic field is determined by curvature induced dynamic demagnetization fields. At high magnetic fields transverse to the tube axis, the three-dimensional shape anisotropy of the tube results in spin-wave confinement in well-defined regions along the tube perimeter.
[show abstract][hide abstract] ABSTRACT: We have studied the spin dynamics of microscopic permalloy rings at GHz frequencies. Increasing the irradiation power, we observe first nonlinear spin dynamics and second microwave-assisted switching (MAS). We explore the MAS phase diagram as a function of microwave power and frequency f and, in particular, extract the critical microwave field hc(f). Its frequency dependence reflects characteristic eigenfrequencies from both the linear and nonlinear spin-wave spectrum. By comparing hc(f) with the different susceptibilities, we gain insight into the microscopic processes which might be the basis of a predictive theory of MAS.