Optical absorption zeeman spectroscopy of rare earth orthochromites

The optical absorption spectrum of Er³⁺ in ErCrO₃ in the phasesΓ ₁,Γ ₂ andΓ ₄ has been studied as a function of temperature and applied magnetic field. The experimental data for the Er³⁺ ground doublet splitting are analyzed using a single ion molecular field approach. The analysis shows that the Cr — Er interaction is predominantly antisymmetric exchange, the magnetic dipole-dipole interaction being an order of magnitude smaller. The Er — Er interaction is of exchange as well as of dipolar origin.