Exciton migration in a ‘‘pseudo’’-one-dimensional crystal: Luminescence dynamics of doped CsMnBr3

The exciton migration in CsMnBr3 (CMB), a linear chain salt which acts as a ‘‘pseudo’’-one-dimensional antiferromagnet, has been probed by examining the time-resolved luminescence of doped crystals. A number of metal ions such as Cr2+, Cr3+, Fe2+, Cu2+, Mo3+, Er3+ were observed to behave as exciton traps, while Cd2+ and Mg2+ act as exciton scatterers (antitraps). Samples doped with traps and traps along with scatterers, as well as ‘‘dilute’’ CsMnx[Mg2+ or Cd2+ ]1−xBr3 crystals were investigated. Analysis of the data indicates that exciton migration between chains is significant with a room temperature hopping frequency of 107–108 s−1 and a thermal barrier of 500 cm−1. The barrier for intrachain migration appears to be somewhat smaller, between 350 and 400 cm−1. Only at temperatures below 60 K does the exciton migration seem to be strictly confined to one dimension.