We present an analytic and numerical study of the creation of a unidirectional spin-wave emission in ultrathin ferromagnetic films sandwiched in an asymmetric layer stack. For this we extend the analytical description of spin waves in spin-wave waveguides by incorporating the influence of the interfacial Dzyaloshinskii-Moriya interaction on the spin-wave propagation. By exploring the model system ${\mathrm{Ni}}_{81}{\mathrm{Fe}}_{19}/\mathrm{Pt}$, we show that it is possible to achieve a unidirectional spin-wave emission by combining wave-vector selective excitation sources with the frequency splitting that arises from the interfacial Dzyaloshinskii-Moriya interaction. Hereby, we focus on device feature sizes and spin-wave wavelengths that are compatible with state-of-the art excitation and detection schemes. We demonstrate that the presented analytical formalism allows for an approximate prediction of the nonreciprocal emission.

• Received 24 November 2016
• Revised 14 January 2017

DOI:https://doi.org/10.1103/PhysRevB.95.064429