Spin-wave canting induced by the Dzyaloshinskii-Moriya interaction in ferromagnetic nanowires
AbstractThe Dzyaloshinskii-Moriya interaction (DMI) can cause spin-wave (SW) nonreciprocality in extended magnetic films. Here, we report a correlated effect for SWs propagating in a waveguide, namely, a longitudinally magnetized nanowire. Due to the shape confinement, SWs traveling in the wire are quasiquantized along the width direction. In the presence of the DMI, the wave-front lines become oblique with respect to the propagation direction, unlike any ordinary wave pattern. The tilting direction of the wave front is determined by the sign of the DMI constant, manifesting the chiral nature of the DMI. Another remarkable SW property revealed is that the two dynamical magnetization components that jointly characterize a SW mode exhibit different spatial profiles. Mathematically, these extraordinary effects can be attributed to the first-order spatial derivative brought into the wave equation by the DMI.