RESUMEN
We report on magnetic and magnetoelastic measurements for a 5000 Å (110) SmFe(2) thin film, which was successfully analyzed by means of a point charge model for describing the effect of the epitaxial growth in this kind of system. Some of the main conclusions of the Mössbauer and magnetoelastic results and the new magnetization results up to 5 T allow us to get a full description of the crystal electric field, exchange, and magnetoelastic behavior in this compound. So, new single-ion parameters are obtained for the crystal field interaction of samarium ions, A(4)(r(4)) = +755 K/ion and A(6)(r(6)) = -180 K/ion, and new single-ion magnetoelastic coupling B(γ,2) is approximately equal -200 MPa and B(ε,2) is approximately equal MPa, which represent the tetragonal and the in-plane shear deformations, respectively. Moreover, the new thermal behavior of the samarium magnetic moment, the exchange coupling parameter, and the magnetocrystalline anisotropy of the iron sublattice are obtained too. From these, the softening of the spin reorientation transition with respect to the bulk case could be accounted for.
RESUMEN
We have investigated the magnetoelastic nature of the dodecagonal anisotropy in the magnetic anisotropy energy (MAE) in the basal plane of the hcp crystalline structure in holmium single crystal. We have proved that the origin of the second harmonic of the hexagonal symmetry in MAE clearly lies on a sixth-order magnetoelastic coupling term. The appearance of a 12-fold anisotropy in MAE in a single crystal having hexagonal symmetry provides a new insight on how the magnetic anisotropy can be modified in a magnetic material with giant spin-lattice coupling.
RESUMEN
We report on the change of the easy axis direction in holmium, from the a to the b axis, under the application of a magnetic field in the basal plane. This spin reorientation is observed by measuring the magnetic torque in Ho(n)/Lu(15) superlattices (n and 15 are the number of atomic planes in the Ho and Lu blocks). We also observe that, at the field H0 and temperature at which the reorientation occurs, both axes are easy directions. Based on the fact that the field H0 depends on n in the same way as the field-induced magnetoelastic distortion does, we propose that this spin reorientation originates from the strong field-induced magnetoelastic deformation within the basal plane. The modulation of the alpha strains with sixfold symmetry originates a 12-fold term in the magnetic anisotropy energy.