MAGNETOOPTIC PROPERTIES OF ORTHOCHROMITES

The spectral dependences of the equatorial Kerr effect in rare-earth orthochromites Lu 1−x Y x CrO 3 (x=0, 0.15, 0.5) have been determined in the photon energy range 3.5-5.2 eV. The orthochromites exhibit a considerable magnetooptic activity at photon energies 4.0-4.8 eV, related to an allowed electric-dipole 2t 2g -7t 1u (3d-4p) transition in a (CrO 6 ) 9− octahedral complex. An analysis of the temperature and magnetic-field dependences of the Kerr effect indicates the existence of a high-temperature phase Γ 4 and a spin-flip transition Γ 4 -Γ 2 at temperatures 90-115 K in LuCrO 3 , in agreement with magnetostriction measurements