Structural, ferroelectric, electronic and transport properties of BaTiO3/Pt heterostructures grown on MgO(0 0 1)

Abstract

Heteroepitaxial BTO(001)/Pt(001) films are grown on MgO(001) by PLD.As grown BTO films are in a single-domain state and polarized downward.The band gap of ultrathin heteroepitaxial BTO layer strongly depends on thickness.Cr/BTO(3nm)/Pt based FTJ: tunneling electroresistance Rup/Rdown up to 30. In this work, we describe the structural and ferroelectric properties of BaTiO3(001)/Pt(001) heterostructures grown by pulsed laser deposition on MgO(001) substrates. By combining HAXPES results on the electronic band line-up at the interfaces of Cr/BaTiO3(001)/Pt(001) trilayers with REELS data of the band gap in ultrathin BaTiO3 layers we reconstruct the shape of the potential energy barrier profile across the corresponding ferroelectric tunnel junction (FTJ). I-V characteristics of FTJs with sub-µm Au/Cr top electrodes reveal a tunneling electroresistance change by the factor of ~30 following the ferroelectric polarization reversal. I-V curves are fitted with the experimentally determined electrostatic potential energy profile for the particular polarization direction to derive the quantitative changes in the barrier profile upon polarization reversal.