Magnetostriction of hcp and dhcp Co‐Fe single crystals

Magnetostriction was measured at room temperaure in various crystallographic directions in hcp Co–0.63 at.% Fe and dhcp Co–2.28 at.% Fe single crystals using a strain‐gauge technique in magnetic fields up to 16 kOe. Anomalous strain variations were observed for the ac plane of a dhcp crystal when the field was parallel to the c axis. Marked differences in the magnetostriction constants were found to exist between the hcp and dhcp crystals. For example, the fractional change in volume associated with domain rotation from the c axis to the basal plane was found to be contraction, −30×10−6, for the hcp crystal, while there was an expansion, +6×10−6, for the dhcp crystal.