Half-metallic interface with stronger ferromagnetism in (110)-oriented La_xSr_1-xMnO₃/SrTiO₃ ultrathin superlattices

Using the density functional calculations, we elucidate the nature of (110)- and (001)-oriented La_xSr_1-xMnO₃/ SrTiO₃ ultrathin superlattices with different La concentrations. In comparison to the (001)-oriented superlattice, the (110)-oriented one keeps ferromagnetic and half-metallic in a wider x range and has much greater exchange energy at the same La concentration, verifying previous experimental results. The significant advantages of the (110) superlattice is the result of the uniform distribution of the e_g states in the 110 superlattice. We also find that the exchange energy is not sensitive to the strain between the layers.