Exchange interaction in MnPt/FeCo sputtered multilayers

MnPt single-layer films have been prepared on glass substrates by RF magnetron sputtering for studying the composition dependencies of resistivity and crystalline structure. In the as-deposited state, the resistivity increases with Mn content and reaches the maximum at 69 at%. By annealing, the resistivity of the films having the Mn content around 51 at% increases, closely relating to the growth of the ordered CuAu FCT-type MnPt crystals. For the both film structures of the glass/Cu/FeCo/MnPt/Cu and the glass/MnPt/FeCo/Cu, which have been sputter-deposited on glass substrates, the exchange interaction between MnPt and FeCo layers, and the coercivity of the FeCo layer have been examined as functions of the Mn content, the layer thickness and the annealing temperature, In the as-deposited state, the exchange field (H-ex) is nearly zero up to 75 at% of Mn content, above which the value of H-ex increases and shows the maximum at 85 at%, in which the blocking temperature is about 100 degrees C. By annealing, the value of H-ex increases for the films of Mn content around 40-60 at%, exhibiting the higher blocking temperature than 360 degrees C. The temperature stability has also been examined using the Rutherford backscattering spectrometry. (C) 2000 Elsevier Science B.V. All rights reserved.