Field-Induced Davydov Splitting of Excitons in Quasi-One-Dimensional Antiferromagnet CsMnCl3·2H2O

Optical absorption spectra corresponding to the 6 A 1 g → 4 T 2 g ( D ) transition in CsMnCl 3 ·2H 2 O have been investigated under magnetic field. In this compound, a sharp exciton line in the lowest energy region of the transition is split by the applied field perpendicular to the spin direction. From the analysis of the spin configuration, this splitting was proved to be a Davydov splitting induced by the field. The field-induced Davydov splitting can be explained by the fact that in an external magnetic field perpendicular to the spin direction, spins cant towards the field so as to remove the prohibition of the inter-sublattice exciton transfer. The field dependence of this splitting is explained by the exciton transfer due to the anisotropic exchange interaction.