Field Dependence of Short Range Ordered State Susceptibility in an S=5⁄2 Heisenberg Linear Chain Antiferromagnet

抄録

Magnetic field dependences of the isothermal susceptibilities in a typical S=5⁄2 Heisenberg linear chain antiferromagnet, CsMnCl₃·2H₂O, were measured in fields between 20 kOe and 45 kOe and at temperatures between 10 K and 15 K. It was observed that there was a considerable dependence of the susceptibilities on the external field.
The field dependence is explained theoretically in the classical spin (S→∞) limit. The partition function in the presence of the external field is expanded in powers of (H⁄T). Consequently, the susceptibility is expressed in powers of (H⁄T) whose coefficients are given by the higher order spin correlation functions in zero field. A quantitative agreement between the theory and the experiment is attained with no adjustable parameter.