Magnetoelastic superstructure in a ferromagnetic film

A study is made of a magnetoelastic (ME) superstructure in a film of a uniaxial ferromagnet with the easy magnetization axis parallel to its surface. The existence of the spatially modulated phase is determined entirely by the magnetostriction coupling of magnetization to lattice deformation at the ferromagnet-substrate interface. In the vicinity of the second-order magnetic orientational phase transition (OPT) induced by an external magnetic field H the static distribution of magnetization and elastic strain in the domain phase is found to be closed to the distribution for the critical Love mode in the homogeneous phase. Apart from the OPT the width of domains increases drastically with H decreasing. It is shown that the singular defects (dislocations and disclinations) appear in the regular domain structure in the vicinity of the OPT, and such defects destroy the long-range order in the ME superstructure. The calculation is extended to ME superstructures in a film of a two-sublattice orthoferrite.