Abstract
An extended Green's function method is presented for a localized antiferromagnetic (AF) system with mixed AF and ferromagnetic couplings, and single-ion anisotropy. Expressions are given for the Néel temperature, the temperature-dependent magnetic order parameter (MOP), and the spin component along the preferred direction of the single-ion anisotropy in the ground state for -type AF . These predict the MOP found by inelastic neutron scattering. Our theory exhibits a nontrivial internal consistency with four measured parameters, including . Our theory also predicts a temperature-dependent spin energy gap that is different from the Holstein-Primakoff theory.
- Received 12 March 2004
DOI:https://doi.org/10.1103/PhysRevB.70.014406
©2004 American Physical Society