Experimental study of spin-wave dispersion in Py/Pt film structures in the presence of an interface Dzyaloshinskii-Moriya interaction

Brillouin light scattering (BLS), complemented by ferromagnetic resonance (FMR) characterization, has been used for studying spin-wave (SW) propagation in Py(L)/Pt(6-nm) bilayers of various Py thicknesses (4 nm <= L <= 10 nm). The FMR measurements allowed determination of the pertinent magnetic parameters and revealed the existence of a normal surface anisotropy. A pronounced asymmetry of Damon-Eshbach (DE) wave frequencies has been evidenced by BLS. Therefore, the difference between Stokes and anti-Stokes DE frequencies has been measured versusSWwave number for all the samples. A detailed discussion about the origin of this frequency difference is reported, which concludes that this is due to interface Dzyaloshinskii-Moriya interaction (IDMI).