Selected formation of a variant in L10-type CoPt realized by ordering heat treatment under a magnetic field

The effect of a magnetic field on disorder–order transformation in a Co–50 at.% Pt alloy has been investigated. A single variant of the L10-type CoPt is obtained when heat treatment is performed under a magnetic field of >0.5 T applied in the 〈0 0 1〉A1 direction, which becomes the easy axis of the single variant in the ordered phase. In addition, the magnetic field is found to be especially effective at the early stage of ordering heat treatment.