First-principles study on the phase diagram and multiferroic properties of(SrCoO3)1/(SrTiO3)1 superlattices

Abstract

To design a multiferroic material at atomic scale, strong spin-lattice and charge-lattice couplings play crucial roles. Our first-principles calculation on(SrCoO3)1/(SrTiO3)1superlattices, with above coupling properties, yields a rich physical phase diagram as a function of epitaxial strain. In particular, a robust ferroelectric ferromagnetic insulator of Pc symmetry is stabilized at tensile strain δa/a0 = 0.86%-5.53%. The polarization can be as large as 36μC/cm2 and magnetic moment can reach 6μB per unit cell. The magnetocrystalline anisotropy energy (0.16meV/Co in (001) plane, 6meV/Co in (100) plane) is comparable with that of TbMnO3compound and the magnetoelectric constantα(1.44 × 10-3Gaussian unit) is comparable with that of Co3B7O13Br compound. Our study suggests that epitaxially strained (SrCoO3) 1/(SrTiO3)1superlattices not only offer an excellent candidate for multiferroic materials, but also demonstrate the half-metal and ferromagnetic insulator properties with potential application in spintronic devices.