Exchange coupling of radio frequency sputtered NiMn/NiFe (NiMn on top) and
NiFe/NiMn (NiMn at bottom) bilayers have been investigated. It was found th
at the exchange coupling field, H-ex, is not only directly related with the
annealing temperature and time, but also is greatly influenced by the thin
film deposition conditions. It was demonstrated that successful antiferrom
agnetic-ferromagnetic bilayer preparation should avoid interfacial contamin
ation, which could destroy the spin coupling at the interface. The NiFe/NiM
n bilayers show a high exchange coupling field [307 Oe for NiFe(200 Angstro
m)/NiMn(500 Angstrom)] bilayer with a high blocking temperature around 430
degrees C. Most important is that the coupling field was able to sustain it
s strength up to almost 270 degrees C before starting to decrease. X-ray di
ffraction reveals that the diffraction intensity of NiMn in as-deposited bi
layers does not seem important to achieve a high exchange coupling field. F
urthermore, the NiMn thickness dependence of the magnetic properties of NiM
n/NiFe bilayer and the NiFe thickness dependence of magnetic properties of
NiFe/NiMn bilayers have been investigated and explored. (C) 1999 American I
nstitute of Physics. [S0021-8979(99)33708-7].