The study of magnetic properties of NiAs-type ferromagnetic/antiferromagnetic multilayer films

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NiAs-type multilayer films consisting of ferromagnetic MnSb and antiferromagnetic CrSb were prepared by a dual-type rf sputtering method on glass substrates. Two targets were used: one was a MnSb alloy target, and the other was a Cr target on which some Sb sheets were placed. The multilayer period was designed in the range from 50 to 200A^^ﾟ, keeping the thickness of MnSb and CrSb layers equal. The X-ray diffraction results indicated that all the multilayer films had a strongly preferred [110] orientation perpendicular to the film plane. However, the multilayer periodicity was not confirmed because the atomic scattering factors of Mn and Cr are very close to each other. The magnetization at low temperatures measured in MnSb/CrSb multilayer films were somewhat larger than that in a MnSb compound. The Curie temperature was also found to decrease with decreasing the multilayer period. One reason of these results is considered to be the interdiffusion near the interface. The temperature dependence of magnetization showed a bend at about 100K and 180K. These bends are considered to result from the modulated exchange interaction.Heusler compound type multilayer films consisting of ferromagnetic PtMnSb and antiferromagnetic CuMnSb were also prepared. The magnetization behavior in PtMnSb/CuMnSb multilayer films showed two peculiar characteristics: (i) a great enhancement of magnetization at low temperatures, and (ii) a bend in the temperature dependence of magnetization at about 50K near the Neel temperature of CuMnSb. These results are of much interest, being similar to the MnSb/CrSb case. For the future, we must search for the systematic understanding of the magnetization behavior in the ferromagnetic/ antiferromagnetic multilayer films in terms of the modulated exchange interaction.