We prove the existence of Néel-type long-range order in the ground state of the spin-1/2 XXZ model with ´(exchange anisotropy) > 1.67 on the square lattice. We further show the existence of long-range order for ´>1.10 and 0≰´<0.59 by assuming monotonicity of nearest neighbor correlations as functions of the system size. The assumption of monotonicity is supported by numerical calculations.
ASJC Scopus subject areas
- Physics and Astronomy(all)