Magnetic behavior of CuBr2⋅2DMSO, a quasi‐Heisenberg S=(1)/(2) antiferromagnetic chain

We report the results of low‐temperature susceptibility and magnetization studies of both protonated and deuterated samples of the title compound, CDB. The single‐crystal susceptibilities can be modeled as arising from a 1‐d Heisenberg S= (1)/(2) chain with an exchange constant J/k=−11.3±0.3 K. This value is consistent with that determined previously from birefringence measurements. The susceptibilities along the a and c axes show indications of spin canting. At 1.5±0.1 K, there are distinct changes in slope in the susceptibilities. The results are similar for the two versions, but the feature is more pronounced for the deuterated compound. This anomaly is consistent with the existence of the critical temperature found in deuterated CDB by neutron scattering. An additional feature is found near 2.6 K in the protonated version; its origin is unclear.