The quasi-1D antiferromagnet CsMnCl3.2H2O. II. A 54Mn nuclear orientation study

Abstract

For pt.I see ibid. vol.1, p.179 (1989). An in situ 54Mn nuclear orientation (NO) study of a quasi-1D antiferromagnet CsMnCl3.4H2O is presented and discussed. From a comparison between CsMnCl3.2H2O, and the 3D antiferromagnet MnCl2.2H2O, it is shown that there are significant differences in the NO behaviour. For example, in zero applied field, the 54Mn nuclei in CsMnCl3.2H2O can be cooled to much lower temperatures than those in MnCl2.4H2O. However, in the presence of applied magnetic fields, a strong reduction in the NO signal is observed in CsMnCl3.2H2O, in marked contrast to MnCl2.4H2O in which rapid decrease in the nuclear spin-lattice relaxation time T1 occurs. It is argued that many of the unexpected features observed in the quasi-1D antiferromagnet can be understood, at least qualitatively, in terms of both 'solitons' and a large zero-point motion of the Mn2+ spins. NO measurements taken in both the axial and equatorial directions reveal that there are about 12.5% spin flopped domains (solitons), in zero applied field. On the other hand, thermometric methods have been used to show that the hyperfine splitting of 54Mn nuclei in CsMnCl3.2H2O is 356(15) MHz.