Effect of the surface polarization in polar perovskites studied from first principles.pdf

Effect of the surface polarization in polar perovskites studied from first principles M. Fechner,1 S. Ostanin,1 and I. Mertig1,2 1Max-Planck-Institut f¨ur Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Saale), Germany 2Martin-Luther-Universit¨at Halle-Wittenberg, Fachbereich Physik, D-06099 Halle, Germany (Dated: February 21, 2008) The (001) surfaces of polar perovskites BaTiO3 and PbTiO3 have been studied from first principles at T=0 K. For both cases of polarization, the most stable TiO-terminated interfaces show intrinsic ˚ ferroelectricity. In the topmost layer, where the O atoms are 0.1 A above Ti, this leads to metallic 8 instead of the insulating behavior of the electronic states that may have important implications for 0 multiferroic tunneling junctions. 0 2 PACS numbers: 31.15.A-, 68.47.Gh, 73.20.At, 77.84.Dy, 77.80.-e b e F Epitaxial growth technique opens the way to combine first principles.17 Table I collects the experimental data 1 ferroelectrics (FE) and ferromagnets (FM) into multi- for the lattice parameters and atomic positions, obtained 2 component multiferroics, which are inaccessible by tra- for the room-temperature tetragonal phase of PTO and ditional synthesis.1,2 Currently, many laboratories across BTO (with space group symmetry P 4mm) and for cu- ] the world work on a prototypic device, consisting of a bic STO (P m − 3m), in comparison with our calcula- i c few-nm thick ferroelectric sand