ESR investigation of the enhancement of the Mn-related red photoluminescence in CaGa2S4 single crystals by rare earth element codoping

Abstract The ternary compound CaGa2S4 doped with Mn exhibits a weak red luminescence which can be strongly enhanced by simultaneous doping with one of some rare earth elements. To clarify this enhancement effect, ESR experiments are carried out on two kinds of single crystals of CaGa2S4; Mn singly doped one and codoped one with La, Ce or Yb. The individual line shapes of the Mn2+ related ESR spectra of the Mn singly doped samples drastically change when codoped with La or Ce which is effective for the enhancement but little with Yb which has no effect. The results of analyzing the ESR data through the calculation of the effective spin Hamiltonian along with studies on photoluminescence spectra strongly suggest that Mn atoms at Ga sites play a main role of the enhancement of the Mn red emission.