HONEYCOMB ISING ANTIFERROMAGNET IN A MAGNETIC-FIELD - INTERFACE TENSION AND CRITICAL-TEMPERATURE

By extending the method due to Muller-Hartmann and Zittartz (1977), the authors calculate the interface tension for the nearest-neighbour antiferromagnetic Ising model on the honeycomb lattice at finite magnetic fields. The calculation reproduces exact interface tension at zero field. From the zero point of the interface tension they derive a compact analytic form of the 'critical frontier' in the (H, T) plane (H: magnetic field, T: temperature), which agrees excellently with the recent 'quasi-analytical' result presented by Wu, Wu and Blote (1989).