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MM: Fachverband Metall- und Materialphysik

MM 26: Functional Materials V: Functional Materials

MM 26.4: Vortrag

Dienstag, 17. März 2015, 12:30–12:45, TC 010

Memristive behavior of TiO_2−δ rutile phases – an ab-initio based ground-state analysis — •Wolfgang Heckel¹, Michael Wehlau², Sascha B. Maisel¹, Thomas Frauenheim², Jan M. Knaup², and Stefan Müller¹ — ¹Institute of Advanced Ceramics, Hamburg University of Technology, D-21073 Hamburg — ²Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen

Memristive devices for various technical applications, e. g. electronic analogues to nerve cells for neuromorphic computing^[1], attract growing attention. TiO₂ has been shown to serve as a memristive material.^[2]

We conducted a comprehensive ab-initio based ground-state search for TiO_2−δ rutile phases in order to identify structural features which lead to the conductive phase of a TiO₂ memristor. A cluster expansion Hamiltonian, fitted to DFT data, enabled us to scan the entire configuration space of the oxygen vacancies. We find that O vacancies tend to form planar arrangements which relax into structures exhibiting metallic behavior. These structures are energetically less favorable, but show an even more pronounced metallic DOS than the Magnéli phases, which do not appear in our calculations due to energy barriers. Our results confirm the relation between vacancy ordering and metallic behavior in reduced oxides.

Supported by DFG, SFB 986, project A4.

[1] Jo, et al., Nano Letters 10, 1297 (2010).

[2] Strukov, et al., Nature 453, 80 (2008).