Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 67: Competition for the Gerhard Ertl Young Investigator Award
O 67.2: Vortrag
Donnerstag, 14. März 2013, 11:00–11:30, H45
Emergent quantum size effects at surfaces of correlated and topological solids — •Phil King — Kavli Institute for Nanoscale Science, Cornell University, USA
We use angle-resolved photoemission (ARPES) to probe quantum-confined electron systems created, at the surfaces of correlated oxides and topological insulators, by control of surface charge. In transition-metal oxides, we write this directly by forming surface oxygen vacancies through UV light irradiation. We use ARPES to image the d-electron subband ladder of the resulting oxide two-dimensional electron liquids, revealing a delicate interplay between quantum-confinement, orbital ordering, spin-orbit interactions and electronic correlations.1,2 In topological insulators, we show that creation of similar surface quantum wells leads to a hierarchy of electronic states with simultaneous confinement of electron- and hole-like subbands,3−5 the former showing giant tuneable Rashba spin splittings.4,5 We uncover a complex band and binding energy dependence of the coupled spin-orbital texture of this surface electronic system through circular dichroism in ARPES. We show how this results from a novel connectivity between quantum well and topological surface states, enforced by the topologically non-trivial nature of the host system.5 Together, these studies reveal the drastic reconstruction of electronic structure that occurs from electric field-induced confinement across a variety of emerging quantum materials. 1 Nature Mat. 10 (2011) 114; 2 Phys. Rev. Lett. 108 (2012) 117602; 3 Nature Commun. 1 (2010) 128; 4 Phys. Rev. Lett. 107 (2011) 096802; 5 Nature Commun. 3 (2012) 1159.