LOW-TEMPERATURE TRANSPORT OF MAGNETIC EXCITONS IN THE QUASI-ONE-DIMENSIONAL ANTIFERROMAGNET CSMNCL3-CENTER-DOT-2H(2)O DOPED WITH CU2+ IONS

The emission decay kinetics and relative quantum yields of exciton lum inescence of Cu2+-doped (3%) quasi-one-dimensional antiferromagnetic c rystals CsMnCl3 . 2H(2)O have been studied in the temperature range fr om 4.2 to 77 K. The experimental emission decay curves have been appro ximated by the calculated curves obtained using computer simulation of incoherent excitons motion. The model assumes a slow interchain hoppi ng process and a rapid intrachain migration of excitons. Exciton hoppi ng (W) and trapping (U) rates at 4.2-77 K have been defined. A decreas e of both U and W rates has been observed with a temperature lowering. The proposed model of exciton migration and trapping considered excit ation passing potential barriers between Mn2+-Mn2+ and Mn2+-Cu2+ ions. To describe the deviation of U(T) and W(T) dependences from the Arrhe nius law we suppose that excitons pass barriers by both hopping over i t and tunneling. The energies and shapes of the barriers have been est imated. The tunneling processes were taken into account while determin ing the barriers energy. The role of both the exciton-phonon interacti on in CsMnCl3 . 2H(2)O and the spin forbiddeness of the low-temperatur e (T less than or equal to 30 K) exciton migration along a chain due t o the antiferromagnetic spin ordering has been discussed.