Magnetic and optical properties of single-crystal CsFeF₃

CsFeF3 appears to be a Néel type ferrimagnet whose magnetization forms cones of revolution having a 25-deg angle with the hexagonal c axis. The moment along the cone angle increases in an anomalous manner in fields up to 25 kG. In addition, the anisotropy energy at 4.2°K is extremely large with K1≈-7.8×106 ergs/cm3 and K2≈2.2×107 ergs/cm3. At room temperature the optical absorption coefficient is about 1 cm-1 for wavelengths 6000-8000 Å. In a field of 20 kG at 84°K the Faraday rotation is 100 deg/cm for a wavelength of 6000 Å. © 1970 The American Institute of Physics.