Brillouin light scattering investigations of exchange biased (110)-oriented NiFe/FeMn bilayers

Abstract

All contributing magnetic anisotropies in (110)-oriented exchange biased Ni80Fe20TFe50Mn50 double layers prepared by molecular beam epitaxy on Cu(110) single crystals have been determined by means of Brillouin light scattering. Upon covering the Ni 80Fe20 films by Fe50Mn50, a unidirectional anisotropy contribution appears, which is consistent with the measured exchange bias field. The uniaxial and fourfold in-plane anisotropy contributions are largely modified by an amount, which scales with the Ni 80Fe20 thickness, indicating an interface effect. The strong uniaxial anisotropy contribution shows an in-plane switching of the easy axis from [110] to [001] with increasing Ni80Fe20-layer thickness. The large mode width of the spin wave excitations, which exceeds the linewidth of uncovered Ni80Fe20 films by a factor of more than six, indicates large spatial variations of the exchange coupling constant. © 1998 American Institute of Physics.