Engineering polarons at a metal oxide surface

Yim, C. M. and Watkins, Matthew and Wolf, M. J. and Pang, C. L. and Hermansson, K. and Thornton, G. (2016) Engineering polarons at a metal oxide surface. Physical Review Letters, 117 (11). pp. 64021-64025. ISSN 0031-9007

Full content URL: http://dx.doi.org/10.1103/PhysRevLett.117.116402

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Abstract

Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO2(110), using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.

Keywords:Surface Science, Condensed Matter Physics, JCOpen
Subjects:F Physical Sciences > F200 Materials Science
F Physical Sciences > F342 Quantum Mechanics
F Physical Sciences > F321 Solid state Physics
Divisions:College of Science > School of Mathematics and Physics
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ID Code:24091
Deposited On:14 Sep 2016 13:48

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