Patterns of PbTiO3 thin films and nanoparticles deposited on a paraelectric substrate

STACHIOTTI, MARCELO; SEPLIARSKY. MARCELO

Congreso; XIX INTERNATIONAL MATERIALS RESEARCH CONGRESS 2010; 2010

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } --> We investigate the interface effects on the polarization pattern of PbTiO3 thin films and nanoparticles deposited on a SrTiO3 paraelectric substrate with the use of a first-principles based atomistic approach. We show for ultrathin films that the correlation of atomic displacements across the film-substrate interface is crucial for the stabilization of the ferroelectric state in films a few unit cells thick. In this way, the minimum film thickness for the appearance of a spontaneous polarized domain state is not an intrinsic property of the ferroelectric film but depends on the polarizability of the paraelectric substrate. We show finally that while free-standing PbTiO3 nanoparticles present a vortex ground state, novel polarization patterns appear when the nanoparticles are deposited on the paraelectric substrate.