Classical Heisenberg antiferromagnet on a triangular lattice in the presence of single-ion anisotropy

The Heisenberg antiferromagnet on a triangular lattice is one of the prototype examples of frustrated systems and has been studied for several decades. In the presence of magnetic fields, the system exhibits a phase diagram consisting of exotic phases. At low temperatures successive magnetic phase transitions occur as the magnetic field is increased. We analyze the ground states of the system to obtain the critical fields at zero temperature. It is also shown through Monte Carlo simulations that the easy-axis single-ion anisotropy in classical Heisenberg antiferromagnet results in the expansion of the uud-phase region.