Optical properties of Na0.5Bi0.5TiO3 crystals

We report some peculiarities of behavior of domain structure and birefringence ∆n of Na0.5Bi0.5TiO3 crystals. Polarization-optical methods are used to study the domain structure and the birefringence ∆n in temperature interval 25°C÷520°C and axial pressure interval 2.5÷60 bar. Single domain state is achieved by application of axial pressure along [100] and [110] directions at temperature near 500°C. Application of axial pressure ~50 bar along [100] direction leads to switching of the samples into anisotropic single domain state. While application of axial pressure ~0.5 bar along [110] direction results in exposition of visually isotropic state and the state is preserved during a cooling process in temperature interval ~500°C÷240°C. In both cases the anisotropic single domain state is observed at room temperature. It is shown that f axial pressure (2.5÷25 bar) application along [110] direction at room temperature leads to a significant increase of the birefringence. It is supposed that both the peculiarities of Δn behavior and the linear behavior of Δn = f(p) are associated with presence of the nanoregions with various orientations of optical indicatrices and their involvement into the orientation process under the action of axial pressure.

Rotational remagnetization and orientational transitions in submicron YIG films

It is shown that for the quasinormal remagnetization of the submicron YIG films with the normal along the [111] axis, which are in the single-domain state, two types of orientation transitions (OT) due to the influence of easy axes can be distinguished. The nonreciprocity of the FMR spectrum for forward and reverse magnetization due to the influence of easy axes is shown.