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Title: Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO 2 thin films

Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO 2 films terminated by a (1 x 4) in-plane surface reconstruction. Employing photo-stimulated chemical surface doping we induce 2DELs with tunable carrier densities that are confined within a few TiO 2 layers below the surface. Subsequent in situ angle resolved photoemission experiments demonstrate that the (1 x 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. Furthermore, this causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ; ORCiD logo [3] ;  [3] ;  [2] ;  [6] ;  [7] ;  [7] ;  [7] ;  [8] ;  [9] ;  [7]
  1. Paul Scherrer Inst. (PSI), Villigen (Switzerland); Univ. of Geneva, Geneva (Switzerland); Chinese Academy of Sciences, Ningbo (People's Republic of China)
  2. Univ. Wurzburg, Wurzburg (Germany)
  3. Univ. of Geneva, Geneva (Switzerland)
  4. Ecole Polytechnique Federale Lausanne (EPFL), Lausanne (Switzlerland)
  5. Chinese Academy of Sciences (CAS), Beijing (China)
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  7. Paul Scherrer Inst. (PSI), Villigen (Switzerland)
  8. Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ecole Polytechnique Federale Lausanne (EPFL), Lausanne (Switzlerland); ETH Zurich, Zurich (Switzerland)
  9. Univ. of Geneva, Geneva (Switzerland); Paul Scherrer Inst. (PSI), Villigen (Switzerland)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 4; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; anatase titanium dioxide; angle resolved photoemission spectroscopy; two-dimensional electron liquid; lateral patterning; surface reconstruction
OSTI Identifier:
1351790

Wang, Zhiming, Zhong, Z., Walker, S. McKeown, Ristic, Z., Ma, J. -Z., Bruno, F. Y., Riccò, S., Sangiovanni, G., Eres, Gyula, Plumb, Nicholas C., Patthey, L., Shi, M., Mesot, J., Baumberger, Felix, and Radovic, Milan. Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films. United States: N. p., Web. doi:10.1021/acs.nanolett.7b00317.
Wang, Zhiming, Zhong, Z., Walker, S. McKeown, Ristic, Z., Ma, J. -Z., Bruno, F. Y., Riccò, S., Sangiovanni, G., Eres, Gyula, Plumb, Nicholas C., Patthey, L., Shi, M., Mesot, J., Baumberger, Felix, & Radovic, Milan. Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films. United States. doi:10.1021/acs.nanolett.7b00317.
Wang, Zhiming, Zhong, Z., Walker, S. McKeown, Ristic, Z., Ma, J. -Z., Bruno, F. Y., Riccò, S., Sangiovanni, G., Eres, Gyula, Plumb, Nicholas C., Patthey, L., Shi, M., Mesot, J., Baumberger, Felix, and Radovic, Milan. 2017. "Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films". United States. doi:10.1021/acs.nanolett.7b00317. https://www.osti.gov/servlets/purl/1351790.
@article{osti_1351790,
title = {Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films},
author = {Wang, Zhiming and Zhong, Z. and Walker, S. McKeown and Ristic, Z. and Ma, J. -Z. and Bruno, F. Y. and Riccò, S. and Sangiovanni, G. and Eres, Gyula and Plumb, Nicholas C. and Patthey, L. and Shi, M. and Mesot, J. and Baumberger, Felix and Radovic, Milan},
abstractNote = {Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with atomic scale precision on an unprecedented length scale comparable to the Fermi wavelength. To this end, we use pulsed laser deposition to grow anatase TiO2 films terminated by a (1 x 4) in-plane surface reconstruction. Employing photo-stimulated chemical surface doping we induce 2DELs with tunable carrier densities that are confined within a few TiO2 layers below the surface. Subsequent in situ angle resolved photoemission experiments demonstrate that the (1 x 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. Furthermore, this causes strong backfolding of the electronic bands, opening of unidirectional gaps and a saddle point singularity in the density of states near the chemical potential.},
doi = {10.1021/acs.nanolett.7b00317},
journal = {Nano Letters},
number = 4,
volume = 17,
place = {United States},
year = {2017},
month = {3}
}