HEXAGONAL ANTIFERROMAGNETS IN STRONG MAGNETIC-FIELD - MAPPING ONTO BOSE-CONDENSATION OF LOW-DENSITY BOSE-GAS

The ground-state spin structures of hexagonal antiferromagnets such as CsCuCl3 in a strong magnetic field are studied by mapping the problem onto an equivalent Bose-gas problem. The spin system close to the saturation is transformed to a low-density Bose gas which has two minima in the single-particle energy band. The low-density expansion is applied to the Bose system and the ground-state spin structure just below saturation field is determined.