Observations of Short-Range Order by Optical Birefringence in One-Dimensional Antiferromagnets CsNiCl3, RbNiCl3and CsCoCl3

Magnetic short-range order was observed in one-dimensional S =1 Heisenberg (CsNiCl 3 , RbNiCl 3 ) and \(S{=}\frac{1}{2}\) Ising antiferromagnet (CsCoCl 3 ) up to k T ∼10| J | and 3| J |, respectively, by measuring optical birefringences. An isomorphic diamagnet CsMgCl 3 was used, with corresponding states argument, to extract the magnetic contribution Δ n m from the resultant birefringence Δ n in these magnetic systems. The temperature T max , at which the temperature derivative of the magnetic part Δ n m displays a broad maximutm, is in agreement with that predicted by the rigorous theory for the specific heat in each linear chain system.