Exciton Absorption Lines in Antiferromagnetic DyCrO₃

Abstract

The absorption spectrum of DyCrO₃ in the red region was studied with and without a magnetic field. From the Zeeman spectrum of a Dy³⁺ ion, the anisotropy axis of a Dy³⁺ ion was determined to be directed along the axis deviated by ±30° from the b-axis in the ab-plane. The magnitudes of the excitation transfer between the Cr³⁺ ions with parallel spin (0.25 cm⁻¹) and with antiparallel spin (0 cm⁻¹) were obtained by analyzing the exciton lines associated with the Cr³⁺ t_2g^{3 4}A_2g→t_2g^{3 2}E_g transition. Remarkable shifts of the exciton lines were observed in magnetic fields parallel to the b-axis. Magnetic-field dependence of these shifts indicated that they were induced by some Dy³⁺-Cr³⁺ interaction. An electric-dipole line creating a Cr³⁺ exciton and a Dy³⁺ spin flip was also observed, from which a negative dispersion of the Cr³⁺ exciton was found to be at least −16 cm⁻¹.