Electronic structure and magnetism of EuTiO3:: a first-principles study

Density- functional theory calculations were carried out for the multiferroic EuTiO3 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.