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 angstrom)/MnFe(40-400 angstrom)/NiFe(300 angstrom)/Ta(200 angstrom). For the lower interface, NiFe(600 angstrom)/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-degrees-C; both increase initially with the MnFe thickness but become essentially constant for MnFe thicknesses beyond 80 and 160 angstrom, respectively. For the upper interface, MnFe/NiFe(300 angstrom), the anisotropy energy falls in the range of 0.00-0.16 erg/cm2 and the critical temperature in the range of 110-190-degrees-C; again, both increase initially with the MnFe thickness but decrease for MnFe thickness beyond 120 and 360 angstrom, respectively. The correlations between the exchange anisotropy and the MnFe structure determined by x-ray diffraction are identified.