The ground-state properties of a spin-1 Heisenberg ferromagnet with an arbitrary crystal-field potential are studied using the linked-cluster series expansion. In the linked-cluster expansion method quantum and spin-fluctuation correlations have been systematically included. We have obtained the magnetization and susceptibility series at zero temperature for a general lattice. The quantum fluctuations play an essential role in determining the magnetic ordering at T=0. The dependence of magnetic ordering on the crystal-field potentials and the critical values of the crystal-field potential for which magnetic ordering exists are discussed. The observed values of magnetization from the linked-cluster series expansion are appreciably depressed from its mean-field approximation values due to the quantum fluctuations.

• Received 5 August 1994

DOI:https://doi.org/10.1103/PhysRevB.51.3610