Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)

O 27.26: Poster

Dienstag, 24. März 2009, 18:30–21:00, P2

Ab initio investigation of the LiNbO₃(0001) surface — •Simone Sanna¹, Alexander V. Gavrilenko², and Wolf Gero Schmidt¹ — ¹Lehrstuhl für Theoretische Physik, Universität Paderborn, 33095 Paderborn, Germany — ²Norfolk State University, Center for Materials Research, 700 Park Avenue Norfolk, VA 23504 USA

Lithium niobate (LN) is frequently used for various (nonlinear) optical and acoustic applications. While traditional applications mainly exploit LN bulk properties, more recently the (microscopic) surface and interface properties of LN have become important (1). Therefore the understanding and analysis of LN surfaces and interfaces is indispensable to optimise and fully implement LN based devices. Unfortunately up to date very little information is available about the LN surfaces and their structure on atomic level (2). We present here an ab initio simulation of ferroelectric LN (0001) surfaces with different stoichiometry based on density functional theory within the generalised gradient approximation. This approach was recently shown to yield reliable structures and energies for bulk LN both in its paraelectric and ferroelectric phase (3). We discuss the stability of a series of candidate structures with varying stoichiometry and surface reconstructions in dependence of the chemical environment. The effect of the dipole corrections and of the cell size on the total local potential and on the electronic and structural properties of the surfaces are shown in detail.
(1) G. Namkoong et al., Appl. Phys. Lett. 87 (2005), 171107.
(2) S. V. Levchenko et al., Phys. Rev. Lett. 100 (2008) 256101.
(3) W. G. Schmidt et al., Phys. Rev. B 77 (2008), 035106.