Point defects at cleaved Srn+1RunO3n+1(001) surfaces

B. Stöger, M. Hieckel, F. Mittendorfer, Z. Wang, M. Schmid, G. S. Parkinson, D. Fobes, J. Peng, J. E. Ortmann, A. Limbeck, Z. Mao, J. Redinger, U. Diebold

Institut für Angewandte Physik, Technische Universität Wien, 1040 Wien, Austria
Center for Computational Materials Science, Technische Universität Wien, 1040 Wien, Austria
Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, U.S.A.
Institute of Chemical Technologies and Analytics, Technische Universität Wien, 1060 Wien, Austria

Phys. Rev. B 90 (2014) 165438

The (001) surfaces of cleaved Sr3Ru2O7 and Sr2RuO4 samples were investigated using low-temperature scanning tunneling microscopy and density functional theory calculations. Intrinsic defects are not created during cleaving. This experimental observation is consistent with calculations, where the formation energy for a Sr and O vacancy, 4.19 eV and 3.81 eV, respectively, is significantly larger than that required to cleave the crystal, 1.11 eV/(1 × 1) unit cell. Surface oxygen vacancies can be created through electron bombardment, however, and their appearance is shown to vary strongly with the imaging conditions. Point defects observed on as-cleaved surfaces result from bulk impurities and adsorption from the residual gas.

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Corresponding author: Ulrike Diebold (diebold at iap_tuwien_ac_at).