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Two-dimensional electron gas with six-fold symmetry at the (111) surface of KTaO3

Abstract : Two-dimensional electron gases (2DEGs) at transition-metal oxide (TMO) interfaces, and boundary states in topological insulators, are being intensively investigated. The former system harbors superconductivity, large magneto-resistance, and ferromagnetism. In the latter, honeycomb-lattice geometry plus bulk spin-orbit interactions lead to topologically protected spin-polarized bands. 2DEGs in TMOs with a honeycomb-like structure could yield new states of matter, but they had not been experimentally realized, yet. We successfully created a 2DEG at the (111) surface of KTaO3, a strong insulator with large spin-orbit coupling. Its confined states form a network of weakly-dispersing electronic gutters with 6-fold symmetry, a topology novel to all known oxide-based 2DEGs. If those pertain to just one Ta-(111) bilayer, model calculations predict that it can be a topological metal. Our findings demonstrate that completely new electronic states, with symmetries not realized in the bulk, can be tailored in oxide surfaces, promising for TMO-based devices.
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http://hal.in2p3.fr/in2p3-00939913
Contributor : Christine Hadrossek <>
Submitted on : Friday, January 31, 2014 - 9:38:43 AM
Last modification on : Monday, January 4, 2021 - 10:48:05 AM

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C. Bareille, F. Fortuna, T. C. Rodel, F. Bertran, M. Gabay, et al.. Two-dimensional electron gas with six-fold symmetry at the (111) surface of KTaO3. Scientific Reports, Nature Publishing Group, 2014, 4, pp.3586. ⟨10.1038/srep03586⟩. ⟨in2p3-00939913⟩

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