LINEAR-CHAIN ANTIFERROMAGNETISM IN [(CH3)4N][MNCL3]

This paper reports optical and magnetic properties of tetramethyl ammonium manganese trichloride, [(CH3)4N][MnCl3]. Magnetically, the system is one of very weakly interacting chains of Mn++ ions. Magnetic-susceptibility measurements are given from room temperature to below 1°K and show a possible phase transition at 0.84°K. Theoretical analysis reveals that the system approximates very closely a Heisenberg linear-chain antiferromagnet with interchain interactions many orders of magnitude smaller than intrachain exchange J. We find J=6.3°K and a susceptibility maximum at 55°K. The optical spectrum shows certain features that are not easily accounted for by an isolated MnCl6 cluster, and may contain information concerning the nature of low-temperature dynamics of the Heisenberg linear chain, although no positive identification of magnon sidebands has yet been made. © 1969 The American Physical Society.