Magnetic properties of MnPt and CoPt

Magnetization measurements were conducted on ordered and disordered polycrystalline specimens of MnPt and three Co‐Pt alloys between 4.2 and 293°K. The magnetic data, while confirming the onset of antiferromagnetism in the ordered MnPt, reveal the presence of ferromagnetic regions in the disordered MnPt. Chemical order tends to exert a pronounced (∠30%) adverse effect on saturation magnetization (Ms,0) of the Co‐Pt alloys at 0°K near the equiatomic composition. Meanwhile, the effect of Co concentration on Ms,0 of the Co‐Pt alloys is shown to be appreciable only when the Co content exceeds 50%.