RESUMO
Density-functional theory calculations were carried out for the multiferroic EuTiO(3) using the LDA+U approach. Total-energy calculations for ferromagnetic (F), and antiferromagnetic A-, C-, and G-type arrangements in the cubic phase shows that the ground-state magnetic configuration is G-type antiferromagnetic for U≤6 eV and ferromagnetic for U≥7 eV. Values of first- and second-neighbour exchange integrals have been calculated by mapping the energy difference between the different magnetic configurations to a Heisenberg Hamiltonian. The system seems to be critically balanced between ferromagnetic and antiferromagnetic states for realistic values of U, and switches from antiferromagnetic to a ferromagnetic ground state on hydrostatic expansion of volume.