Quasi-one-dimensional antiferromagnetism in (CH3NH3)MnCl3⋅2H2O

Abstract

(CH3NH3)MnCl3⋅2H2O, MMC, contains chains of cis-[MnCl4(H2O)2] octahedra corner-linked via single Cl atoms. These chains are very similar to those in CsMnCl3⋅2H2O, CMC, but more widely separated by the larger cations. We have measured the magnetic susceptibilities of MMC between ∼1 and 100 K at 80 Hz and its heat capacity between ∼1 and 20 K. Susceptibilities above ∼10 K are well described by models of the antiferromagnetic linear Heisenberg chain with S=5/2, g=2.00, and J1/k=−3.01 K, very nearly the same intrachain coupling as in CMC. Below TN =4.12 K weak interchain interactions (∼6×10−3‖J1‖) produce long-range AF order in three dimensions with preferred spin alignment along or near the a axis. The linear chains in MMC are more nearly independent than those in CMC.