Magnetic Ordering of the Linear Chain Antiferromagnet CsMnBr3

Results of neutron diffraction, magnetic susceptibility and specific heat measurements on single crystal samples of the hexagonal linear chain compound CsMnBr3 are reported. Three‐dimensional magnetic ordering occurs at TN=8.3°K. Above TN neutron scattering maxima are observed at reciprocal lattice planes, indicative of one‐dimensional correlations along the chain. Below TN the Mn2+ magnetic moments are coupled antiferromagnetically along the chains but lie in the basal plane, where they form a triangular array. The magnitude of the Mn2+ moment extrapolated to 0°K is indicative of a substantial zero‐point spin deviation. From about 90°K to 300 °K the susceptibility data could be fit with Fisher's exact solution for the susceptibility of a classical, nearest‐neighbor, one‐dimensional Heisenberg antiferromagnet. We found J=9.6°K and χmax at 90°K. Evidence of anisotropy was observed in the susceptibility data. The specific heat data below 13°K is dominated by a term linear in T. The coefficient of the linear...