Validity of the Sugano-Tanabe diagram for band states in MnO and MnS under high pressure

Abstract Optical transition between 3d bands in cubic MnO and MnS is measured upon applying hydrostatic pressure. Pressure dependence of the Racah parameter B and the crystal field strength Dq is determined. The pressure coefficients of transition energies from 6 A 1 to 4 T 1 and 4 T 2 states calculated using the Sugano-Tanabe diagram agree well with experimental values. An emission band at 1.63 eV in MnS at 1.5 K. is identified to be 6 T 1 → 4 A 1 transition accompanied by a large lattice relaxation.