MnFe structure-exchange anisotropy relation in the NiFe/MnFe/NiFe system

The relation between the MnFe structure and the exchange anisotropy in the Ni80Fe20/Mn50Fe50/Ni80Fe20 system has been investigated. The samples have a layered structure of glass/NiFe(600 Å)/MnFe(40–400 Å)/NiFe(300 Å)/Ta(200 Å). For the lower interface, NiFe(600 Å)/MnFe, the anisotropy energy falls in the range of 0.00–0.06 erg/cm2 and the critical temperature in the range of 120–160 °C; both increase initially with the MnFe thickness but become essentially constant for MnFe thicknesses beyond 80 and 160 Å, respectively. For the upper interface, MnFe/NiFe(300 Å), the anisotropy energy falls in the range of 0.00–0.16 erg/cm2 and the critical temperature in the range of 110–190 °C; again, both increase initially with the MnFe thickness but decrease for MnFe thickness beyond 120 and 360 Å, respectively. The correlations between the exchange anisotropy and the MnFe structure determined by x-ray diffraction are identified.