Monte Carlo and variational calculations of the magnetic phase diagram of CuFeO ₂

Monte-Carlo and variational calculations are used to revise the phase diagram of the magnetically frustrated material CuFeO ₂. For fields 50<H<65T, a new spin-flop phase is predicted between a canted 3-sublattice phase and the conventional conical spin-flop phase. With wave vector Q(0.8π,0.43π), this phase is commensurate in the x direction but incommensurate in the y direction. A canted 5-sublattice phase is predicted between the multiferroic phase and either a collinear 5-sublattice phase for pure CuFeO ₂ or a canted 3-sublattice phase for Al- or Ga-doped CuFeO ₂.