KIP-Veröffentlichungen

Nonlinear self-phase modulation is a universal phenomenon responsible, for example, for the
formation of propagating dynamic solitons. It has been reported for waves of different physical
nature. However its direct experimental observation for spin waves has been challenging. Here we
show that exceptionally strong phase modulation can be achieved for spin waves in microscopic
waveguides fabricated from nanometer-thick films of magnetic insulator, which support propagation
of spin waves with large amplitudes corresponding to angles of magnetization precession exceeding
10°. At these amplitudes, the nonstationary nonlinear dynamic response of the spin system causes an
extreme broadening of the spectrum of spin-wave pulses resulting in a strong spatial variation of the
spin-wave wavelength and a temporal variation of the spin-wave phase across the pulse. Our findings
demonstrate great complexity of nonlinear wave processes in microscopic magnetic structures and
importance of their understanding for technical applications of spin waves in integrated devices.