The magnetic and multiferroic properties in BiMnO3

In this paper, the magnetic and multiferroic properties in the multiferroic material BiMnO3 are studied. A Heisenberg type Hamiltonian for BiMnO3 is proposed, in which the nearest and farther neighbors are considered. Thermodynamic quantities such as magnetization and magnetic susceptibility for different magnetic orderings under high pressure or magnetic field are calculated, and the simulation results fit the experimental results. Farther neighboring exchanges can result in the coexistence of the ferromagnetic ordering and certain antiferromagnetic ordering with no centrosymmetry. Our study demonstrates that the BiMnO3 should be the type-II multiferroic, and the ferromagnetic and ferroelectric orderings could coexist. The magnetic field control of ferroelectric polarization is also studied. The ferroelectric polarization is always suppressed by the external magnetic field.