Anisotropy in magnetoelastic effects of YCo5

Abstract: We develop the phenomenological theory for uniaxial ferromagnets, and derive explicit formulae for their magnetostriction (MS) and magnetic anisotropy energy (MAE) generated by the magnetoelastic (ME) effects. An analysis of the experimental results for the MS in hexagonal YCo${5}$ using the formulae obtained reveals that 1) an elastic anomaly should appear in the elastic constant $c{33}$, and 2) the MAE caused by the ME effects could be non-negligible. The calculated results of electronic structure under lattice deformation indicate that the particular arrangement of Co atoms in the lattice is related to the anisotropy of MS in YCo$_{5}$. It is suggested that the anisotropic MS observed for various Y-compounds could be interpreted in a similar manner.