Orbital symmetry reconstruction and strong mass renormalization in the two-dimensional electron gas at the surface of KTaO${}_{3}$

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Orbital symmetry reconstruction and strong mass renormalization in the two-dimensional electron gas at the surface of KTaO $_{3}$

A. F. Santander-Syro, C. Bareille, F. Fortuna, O. Copie, M. Gabay, F. Bertran, A. Taleb-Ibrahimi, P. Le Fèvre, G. Herranz, N. Reyren, M. Bibes, A. Barthélémy, P. Lecoeur, J. Guevara, and M. J. Rozenberg

Phys. Rev. B 86, 121107(R) – Published 19 September 2012

Abstract

We study, using angle-resolved photoemission spectroscopy, the two-dimensional electron gas (2DEG) at the surface of KTaO $_{3}$ (KTO), a wide-gap insulator with strong spin-orbit coupling (SOC). We find that this 2DEG is a genuinely different physical state with respect to the bulk: the orbital symmetries of its subbands are entirely reconstructed and their masses are renormalized. This occurs because the values of the SOC, the Fermi energy, and the subband splittings become comparable in the 2DEG. Additionally, we identify an $F$ -center-like heavy band resulting from the polar nature of the KTO surface.

Received 13 July 2012

DOI:https://doi.org/10.1103/PhysRevB.86.121107

Authors & Affiliations

A. F. Santander-Syro^1,2,*, C. Bareille¹, F. Fortuna¹, O. Copie^3,†, M. Gabay⁴, F. Bertran⁵, A. Taleb-Ibrahimi⁵, P. Le Fèvre⁵, G. Herranz⁶, N. Reyren^7,8, M. Bibes^7,8, A. Barthélémy^7,8, P. Lecoeur⁹, J. Guevara¹⁰, and M. J. Rozenberg⁴

¹CSNSM, Université Paris-Sud and CNRS/IN2P3, Bâtiments 104 et 108, 91405 Orsay cedex, France
²Laboratoire Physique et Etude des Matériaux, UMR-8213 ESPCI/UPMC/CNRS, 10 rue Vauquelin, 75231 Paris cedex 5, France
³Universität Würzburg, Experimentelle Physik VII, 97074 Würzburg, Germany
⁴Laboratoire de Physique des Solides, Université Paris-Sud, Bâtiment 510, 91405 Orsay, France
⁵Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin Boîte Postale 48, 91192 Gif-sur-Yvette, France
⁶Institut de Ciència de Materials de Barcelona, CSIC, Campus de la UAB, 08193 Bellaterra, Catalunya, Spain
⁷Unité Mixte de Physique CNRS/Thales, Campus de l’Ecole Polytechnique, 1 Avenue A. Fresnel, 91767 Palaiseau, France
⁸Université Paris-Sud, 91405 Orsay, France
⁹Institut d’Electronique Fondamentale, Université Paris-Sud, Bâtiment 220, 91405 Orsay, France
¹⁰Escuela de Ciencia y Tecnología, Universidad de San Martín, and CONICET, Argentina

^*andres.santander@csnsm.in2p3.fr
^†Present address: CRISMAT, CNRS-ENSICAEN, UMR 6508, 6 boulevard du Maréchal Juin, F-14050 Caen Cedex 4, France.

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Vol. 86, Iss. 12 — 15 September 2012

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