Magnetic susceptibility of [(CH 3) 3NH]NiCl 3·2H 2O and (C 9H 7NH)NiCl 3· [formula omitted]one dimensional S=1 systems with ferromagnetic intrachain interactions

Abstract

The powder magnetic susceptibilities of the new 1 d S=1 systems [(CH 3) 3NH]NiCl 3·2H 2O (henceforth TMAN) and (C 9H 7NH)NiCl 3· 3 2 H 2O (henceforth QNC) have been measured down to T=2 K. Both salts contain bibridged nickel chloride chains. The data reveals strong ferromagnetic intrachain spin correlations in both salts with the onset of long range order at T=3.5 K in TMAN. A theoretical expression for the susceptibility of a 1 d S=1 Ising system with single ion anisotropy has been derived. The results of the analysis are compared with those for high temperature series expansion of a Heisenberg system with single ion anisotropy. Both models give J/ k⋍10–14 K for TMAN and QNC with the M s =0 level low.