Ferromagnetic behavior of disordered MnPt films produced by rf sputtering

The state of atomic order and the variation of magnetic behavior with atomic order in MnPt are studied. X-ray and neutron diffraction experiments show that quenching still results in appreciable degrees (≳0.8) of order and only through sputtering can completely disordered MnPt be prepared. Magnetization measurements conducted on the quenched powder and on the sputtered films established ferromagnetism in the disordered MnPt. The deduced magnetic moment is 3.25±0.30 μB per Mn atom in the sputtered films at 0 °K. This value is compared with those deduced for Mn in other alloys. The difficulties in invoking the Bethe-Slater criterion or a segregation of constituent atoms to explain the onset of ferromagnetism in the disordered MnPt are discussed.