Interface Control of Ferroelectricity in an SrRuO3 /BaTiO3 /SrRuO3 Capacitor and its Critical Thickness.

The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO3 /BaTiO3 /SrRuO3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO2 -BaO and SrO-TiO2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.

[1]  A. Millis,et al.  Whither the oxide interface. , 2012, Nature materials.

[2]  Masaki Kobayashi,et al.  Strong Surface‐Termination Effect on Electroresistance in Ferroelectric Tunnel Junctions , 2015 .

[3]  Sergei V. Kalinin,et al.  Surface Control of Epitaxial Manganite Films via Oxygen Pressure. , 2015, ACS nano.

[4]  E. Tsymbal,et al.  Interface dipole effect on thin film ferroelectric stability: First-principles and phenomenological modeling , 2012 .

[5]  I. Barin.  Thermochemical data of pure substances , 1989 .

[6]  D. Muller,et al.  Why some interfaces cannot be sharp , 2005, cond-mat/0510491.

[7]  D. Bonnell,et al.  Evolution of the Structure and Thermodynamic Stability of the BaTiO 3 (001) Surface , 2008 .

[8]  C. Afonso,et al.  Expansion dynamics of the plasma produced by laser ablation of BaTiO3 in a gas environment , 1997 .

[9]  A. Minor,et al.  Observation of polar vortices in oxide superlattices , 2016, Nature.

[10]  J. Heber.  Materials science: Enter the oxides , 2009, Nature.

[11]  Akira Ohtomo,et al.  A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface , 2004, Nature.

[12]  Jian-Min Zuo,et al.  Lattice and strain analysis of atomic resolution Z-contrast images based on template matching. , 2014, Ultramicroscopy.

[13]  Oxygen-induced surface reconstruction of SrRuO3 and its effect on the BaTiO3 interface. , 2010, ACS nano.

[14]  Aiping Chen,et al.  Strong oxygen pressure dependence of ferroelectricity in BaTiO3/SrRuO3/SrTiO3 epitaxial heterostructures , 2013 .

[15]  D. Vanderbilt,et al.  Ab initio study of BaTiO 3 and PbTiO 3 surfaces in external electric fields , 2000, cond-mat/0009288.

[16]  C. Afonso,et al.  Pressure effects during pulsed-laser deposition of barium titanate thin films , 1998 .

[17]  H. Hwang,et al.  BASIC NOTIONS , 2022 .

[18]  Stephen Jesse,et al.  Dynamic behaviour in piezoresponse force microscopy. , 2006, Nanotechnology.

[19]  A. Tagantsev,et al.  Ionic polarizability of conductive metal oxides and critical thickness for ferroelectricity in BaTiO3. , 2006, Physical review letters.

[20]  H. Hwang,et al.  Two-dimensional normal-state quantum oscillations in a superconducting heterostructure , 2009, Nature.

[21]  J. Junquera,et al.  Critical thickness for ferroelectricity in perovskite ultrathin films , 2003, Nature.

[22]  A. Rappe,et al.  Strong reciprocal interaction between polarization and surface stoichiometry in oxide ferroelectrics. , 2014, Nano letters.

[23]  A. Tagantsev,et al.  Ferroelectricity in asymmetric metal-ferroelectric-metal heterostructures: a combined first-principles-phenomenological approach. , 2007, Physical review letters.

[24]  N. Reyren,et al.  Superconducting Interfaces Between Insulating Oxides , 2007, Science.

[25]  C. Eom,et al.  Enhanced surface diffusion through termination conversion during epitaxial SrRuO3 growth , 2004 .

[26]  S. Ismail-Beigi,et al.  Electronic and Magnetic Properties of SrTiO3/LaAlO3 Interfaces from First Principles , 2010, Advanced materials.

[27]  Hua Zhou,et al.  Anomalous expansion of the copper-apical-oxygen distance in superconducting cuprate bilayers , 2009, Proceedings of the National Academy of Sciences.

[28]  P Yu,et al.  Interface control of bulk ferroelectric polarization , 2012, Proceedings of the National Academy of Sciences.

[29]  Philippe Ghosez,et al.  Interface Physics in Complex Oxide Heterostructures , 2011 .

[30]  J. Mannhart,et al.  Oxide Interfaces—An Opportunity for Electronics , 2010, Science.

[31]  Stephen Jesse,et al.  Switching spectroscopy piezoresponse force microscopy of ferroelectric materials , 2006 .

[32]  Chang-Beom Eom,et al.  Differentiating Ferroelectric and Nonferroelectric Electromechanical Effects with Scanning Probe Microscopy. , 2015, ACS nano.

[33]  C. M. Folkman,et al.  Enhancement of Ferroelectric Polarization Stability by Interface Engineering , 2012, Advanced materials.

[34]  Y. Chang,et al.  Direct Nanoscale Analysis of Temperature-Resolved Growth Behaviors of Ultrathin Perovskites on SrTiO3. , 2016, ACS nano.

[35]  D. Blank,et al.  Structure–Property Relation of SrTiO3/LaAlO3 Interfaces , 2008, 0809.1068.