Monte Carlo simulations of CsMnBr3

Monte Carlo simulations of the magnetic Hamiltonian of CsMnBr3, an XY antiferromagnet on a simple-hexagonal lattice, have been carried in order to examine the phase diagram in an applied magnetic field and the recently discovered tetracritical point. Results on a 12×12×12 lattice reproduce the observed phase diagram. Application of a magnetic field in the ab plane splits the zero-field transition into two transitions. The structures of the two phases are also in agreement with the measurements. Simulations of lattices with a larger number of spins along the c axis reveal a substantial renormalization of the Néel temperature due to the quasi-one-dimensional nature of the Hamiltonian.