Chasing a polar catastrophe: \textit{ab-initio} theory of the LaAlO$_{3}$/SrTiO$_{3}$ interface

ORAL

Abstract

A polar discontinuity at the abrupt oxide/oxide interface is one of several problems that need to be addressed before we can realize the promise of multiferroic oxide structures. To avoid the so-called polar catastrophe the interface undergrows roughening which renders the structure useless, unless the system finds a mechanism for compensating the interface charges. Recent experiments of Hwang and co-workers (\textit{Nature }\textbf{427}, 423-426 (2004) and \textit{Nature }\textbf{430}, 657-661 (2004)) suggest that in the case of perovskite oxides two quite different compensatory mechanisms are at play at the heterojunction. For the n-type LaAlO$_{3}$/SrTiO$_{3}$ interface it is purely electronic involving mixed valence Ti ions, while for the p-type it is an actual ionic reconstruction involving oxygen vacancies. We report a first-principles study of both interfaces within density functional theory. We consider the energetics and electronic structure of the interface, including the role of oxygen vacancies and band offsets. In addition we consider the interface stability with respect to inter diffusion of La and Sr across the interface.

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Authors

  • Dana Dunn

    University of Texas at Arlington, Peoples Friendship University of the Russia, TSAAPT Officer, University of Texas at El Paso, Department of Chemistry, Stephen F. Austin University, Department of Physics, Stephen F. Austin University, Highland Park High School, Dallas, Texas, Lamar High School, Arlington, Texas, Angelo State University, Abilene Christian University, Southern Nazarene University, Texas Tech University, Sam Houston State University, University of Texas at Austin, Cornell University, University of Houston, University of Texas Center for Relativity, Ion Beam Modification and Analysis Laboratory (IBMAL), University of North Texas, University of North Texas, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083, Department of Physics, The University of Texas at Arlington, Arlington, Texas 76019, Department of Physics, University of Texas at Arlington, Arlington, TX, 76019, UTA High Energy Physics Group, Univ. of Texas, Arlington, USA, KAERI Korea, Changwon National Univ., Korea, Rutgers University, Iowa State University, Rigaku/MSC, Texas Christian University, Dept. of Physics, Changwon National University, Department of Physics, University of North Texas, Department of Chemistry and Biochemistry, Arizona State University, Research Center, Philip Morris USA, Harrington Department Bioengineering Arizona State University, Universidad Autonoma de Colima, Universidad de Buenos Aires, Department of Physics, University of Texas, Arlington, Chair, Department of Physics, University of Texas at Arlington, Dean of Science, University of Texas at Arlington, President, University of Texas at Arlington, Department of Electrical Engineering, Princeton University, Department of Physics, Texas A\&M University, NanoFAB Center and Electrical Engineering Department, University of Texas at Arlington, University of Texas at San Antonio, SEMATECH, University of Texas at Dallas, CINVESTAV Queretaro, Mexico and University of Texas at Dallas, Texas A\&M University, Departamento de F\'isica, FCEN, Universidad de Buenos Aires, Freescale Semiconductor, Inc., Department of Physics, UT Austin, Physics Department, The University of Texas at Arlington, Department of Physics, University of Texas at Arlington, Tolar High School, Granbury High School

  • Alex Demkov

    Department of Physics, UT Ausitn, The University of Texas at Austin