Paramagnetic susceptibilities of the antiferromagnetic quantum chain copper chloride bis–dimethyl sulfoxide: Theory and experiment

Copper chloride bis(DMSO) (DMSO is dimethyl sulfoxide) consists of linear chains of antiferromagnetically coupled S=(1/2) ions. The single-crystal dc magnetic susceptibilities of both protonated and deuterated samples of this compound have been measured between 1.8 and 45 K; the susceptibilities of the two versions were identical. Evidence for a small amount of Ising-like anisotropy was seen in the temperature-dependent susceptibilities. The data were compared to the predictions of Bücher and Honerkamp for the behavior of single-crystal susceptibilities of XXZ linear chains. Good agreement was found for an exchange strength of J/$k_B$=-8.25 K and an anisotropy parameter Δ=1.1, slightly Ising-like. The b axis is the easy axis. The results of further theoretical studies on the effect of XXZ anisotropy upon powder susceptibilities of linear chains are presented. A procedure is described for determining both J and Δ for XXZ antiferromagnetic chains from powder data.