Propagation properties of magnetostatic surface spin waves in antiferromagnetic films considering the Dzyaloshinskii–Moriya interaction

Abstract

We theoretically investigate the magnetostatic surface spin waves (MSSWs) and their propagation characteristics in uniaxial antiferromagnetic (AFM) films. In the long-wavelength regime, two distinct MSSW modes appear with either linear or elliptical polarizations, representing mixed states of the right-handed polarized spin waves (RPSWs) and the left-handed polarized spin waves (LPSWs). As the wavevector increases, the two modes are merged together and evolve from mixed states into pure RPSW and LPSW modes. These right- and left-polarized MSSWs exhibit polarization-dependent unidirectional propagation and each mode propagates in opposite directions, localized at either the upper or the lower surface. When a proper external magnetic field is applied, the two MSSW modes can be fully polarized: one as pure RPSW and the other as pure LPSW. Introduction of a bulk generalized Dzyaloshinskii–Moriya interaction with appropriate strength further separates the modes, confining one to the upper surface and the other to the lower surface. The polarization-dependent, surface-selective transport of MSSWs revealed in this study offers a promising route for developing novel AFM-based magnonic devices.