Optical absorption and luminescence studies of the 2D antiferromagnets Rb2MnCl4and Rb3Mn2Cl7

Single crystals of Rb2MnCl4 and Rb3Mn2Cl7 were prepared from the melt. The 6A1 implies/implied by 4T1 (G) transitions were investigated by high-resolution absorption, luminescence and excitation spectroscopy. Sharp fine structure was observed in the overlap region of excitation and luminescence spectra at low temperature. This can be rationalised in terms of pure-exciton, exciton-magnon and exciton-photon transitions. Excitation transfer occurs as a result of the exchange coupling.