Effect of Deformation-Induced Crystal Imperfections on Magnetocrystalline Anisotropy of Nickel Single Crystals

The first magnetocrystalline anisotropy constant of plastically deformed nickel single crystals was studied as a function of deformation. Contributions of specific types of imperfection, viz., interstitials, vacancies, and disclocations on the ``effective magnetic anisotropy constant'' K₁′ were analyzed from the recovery characteristics of K₁′. The dislocation structure of the deformed crystals was investigated by transmission electron microscopy at various stages of recovery. The absolute value of K₁′ increased with deformation. The maximum change occurred at a strain $\text{ε≈0.17}$ with an increase of about 6.5% from the undeformed value of K₁ = −5.52×10⁴±0.02×10⁴ erg/cc measured at 21.5°C and at a magnetic field of 8 kOe. Point defects were not found to have a measurable effect on the recovery of K₁′. Deformation‐induced dislocations were mainly responsible for the observed change. The recovery of K₁′ was interpreted in terms of rearrangement and annihilation of disclocations.