Magnetic field effects on surface spin waves in a body-centered-cubic antiferromagnet

The effect of a magnetic field applied perpendicular to the spin-preferred axis on surface spin waves in a body-centered-cubic antiferromagnet is studied theoretically. The continuum model for the magnetic medium is adopted to study the acoustic mode of surface waves. It is found that the surface spin-wave frequency increases with increasing magnetic field and that the surface mode merges into the bulk spin-wave band if the magnetic field H becomes equal to Hc[2(1+fξ)]12. Here Hc denotes the spin-flop critical field, ξ is the angle between the quantization axis of the surface spin and that of the bulk spin, and f is a numerical factor which is smaller than unity.