POWDER AND SINGLE-CRYSTAL SUSCEPTIBILITY OF THE QUASI-1D HEISENBERG ANTIFERROMAGNETIC CHAIN COMPOUNDS AGVP216 AND AGCRP23-26

The single crystal susceptibility of the isostructural AgVP2S6 (S = 1) and AgCrP2S6 (S = 3 2) antiferromagnetic chain compounds has been measured. The S = 3 2 compound behaves conventionally with a small anisotropy which is attributed to single-ion effects. The S = 1 compound, which exhibits a quantum gap, has a remarkable isotropic behavior and hence is unique in this regard. The previously determined powder susceptibility data are also analyzed and discussed in terms of the Haldane conjecture. © 1990.