Measurements of indices of refraction, birefringence, rotation of optical ellipsoid and optical activity have been made near incommensurate phase transition temperature and near two- and three-dimensional magnetic ordering temperatures in BaMnF//4. The results are compatible with a single first order structural phase transition at T//I equals 251 K. The point group symmetry below T//I is shown to be 2(C//2) or lower. Magnetic contribution to the refractive index at low temperatures is obtained. 9 refs.
Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics