A Mossbauer study of57Fe-doped CsCoCl3

Abstract

The authors report Mossbauer measurements between 1.2 and 300 K for caesium cobalt chloride (CsCoCl3) doped to 1 at.% with 57Fe. CsCoCl3 is a pseudo-one-dimensional Ising-like antiferromagnet; the Co2+ ions are arranged in chains parallel to the hexagonal c axis. The Mossbauer spectra are consistent with the generally accepted magnetic structure of CsCoCl3, namely a transition to a partially three-dimensionally ordered state at 21 K and to complete three-dimensional ordering at 8.5 K. The spectra showed evidence of relaxation, and were fitted using the stochastic model of Blume and Tjon (1968). Two different relaxation processes occurring simultaneously could be distinguished in the spectra between 8.6 and 20 K, namely relaxation between the lower Fe2+ electronic states (in those Fe2+ ions in the three-dimensionally ordered chains) and magnetic HF field reversal (in those Fe2+ ions in the one-dimensionally ordered chains). The latter process could be attributed to solitons moving along the chains; the first process did not appear to be soliton-induced. The Mossbauer parameters could be explained reasonably well using a set of temperature-independent crystal-field parameters.