Nuclear magnetic resonance in CsMnBr₃.2H₂O Cs₂MnBr₄.2H₂O and Rb₂MnBr₄.2H₂O

This paper presents nuclear magnetic resonance results on various nuclei and magnetic phase diagrams of the compounds CsMnBr₃.2H₂O, Cs₂MnBr₄.2H₂O and Rb₂MnBr₄.2H₂O. From the nuclear magnetic resonance data the electric and magnetic interaction parameters are determined and compared with the results in the isostructural chlorine compounds. In the linear-chain antiferromagnetic CsMnBr₃.2H₂O the Néel temperature is 5.75 K, the space group is Pć ć á and dipole calculations indicate a substantial zero-temperature spin reduction. Part of the magnetic phase diagrams of Cs₂MnBr₄.2H₂O and Rb₂MnBr₄.2H₂O are studied and show a meta- magnetic transition for the cesium salt (HA {reversed tilde equals} H_E = 20 kOe). The phase diagrams have been fitted to several models. The appreciable increase in T_N (50%) when going from chlorine to the isostructural bromine compounds can be satisfactorily explained by taking into account the additional increase in the anisotropy.