Magnetostriction and magnetic anisotropy of Fe35Co 65

A Fe35Co65 single crystal has been prepared by a long time anneal at temperature close to its fcc-bcc phase boundary. Its magnetostriction constant λ100 and magnetocrystalline anisotropy constant K1 was measured using a strain gauge rosette and magnetization and torque magnetometer curves. The magnetostriction constant λ 100 is as high as 200 ppm. The value of the anisotropy constant K 1 and the value of the susceptibility were small and influenced by the magnetoelastic energy. The symmetry of the torque curves changes from 2-fold to 4-fold with increasing external field which indicates the existence of a second uniaxial phase. This result can be interpreted by the alignment of the magnetization of an epitaxial fcc precipitate in the bcc host by external field.