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Band structure and spin-orbital texture of the (111)-KTaO 3 2D electron gas

DOI: 10.1002/aelm.201800860 DOI Help

Authors: Flavio Y. Bruno (University of Geneva) , Siobhan Mckeown Walker (University of Geneva) , Sara Ricco (University of Geneva) , Alberto De La Torre (University of Geneva) , Zhiming Wang (Swiss Light Source; Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences) , Anna Tamai (University of Geneva) , Timur K. Kim (Diamond Light Source) , Moritz Hoesch (Diamond Light Source) , Mohammad S. Bahramy (University of Tokyo; RIKEN Center for Emergent Matter Science) , Felix Baumberger (University of Geneva; Swiss Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Advanced Electronic Materials , VOL 44

State: Published (Approved)
Published: March 2019

Abstract: 2D electron gases (2DEGs) in oxides show great potential for the discovery of new physical phenomena and at the same time hold promise for electronic applications. In this work, angle‐resolved photoemission is used to determine the electronic structure of a 2DEG stabilized in the (111)‐oriented surface of the strong spin–orbit coupling material KTaO3. The measurements reveal multiple sub‐bands that emerge as a consequence of quantum confinement and form a sixfold symmetric Fermi surface. This electronic structure is well reproduced by self‐consistent tight‐binding supercell calculations. Based on these calculations, the spin and orbital texture of the 2DEG is determined. It is found that the 2DEG Fermi surface is derived from bulk J = 3/2 states and exhibits an unconventional anisotropic Rashba‐like lifting of the spin‐degeneracy. Spin‐momentum locking holds only for high‐symmetry directions and a strong out‐of‐plane spin component renders the spin texture threefold symmetric. It is found that the average spin‐splitting on the Fermi surface is an order of magnitude larger than in SrTiO3, which should translate into an enhancement in the spin–orbitronic response of (111)‐KTaO3 2DEG‐based devices.

Journal Keywords: 2D electron gas; angle resolved photoemission spectroscopy; KTaO3; oxide electronics; spin–orbit coupling

Subject Areas: Physics, Materials


Instruments: I05-ARPES

Other Facilities: Swiss Light Source