Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO2 Thin Films

Z. Wang; Z. Zhong; S. McKeown Walker; Z. Ristic; J. Z. Ma; F. Y. Bruno; S. Riccò; G. Sangiovanni; G. Eres; N. C. Plumb; L. Patthey; M. Shi; J. Mesot; F. Baumberger; M. Radovic

doi:10.1021/acs.nanolett.7b00317

Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO₂ Thin Films

Z. Wang, Z. Zhong, S. McKeown Walker, Z. Ristic, J. Z. Ma, F. Y. Bruno, S. Riccò, G. Sangiovanni, G. Eres, N. C. Plumb, L. Patthey, M. Shi, J. Mesot, F. Baumberger, M. Radovic

Quantum Heterostructures

Research output: Contribution to journal › Article › peer-review

33 Scopus citations

Abstract

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 × 4) in-plane surface reconstruction. Employing photostimulated 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 × 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. 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.

Original language	English
Pages (from-to)	2561-2567
Number of pages	7
Journal	Nano Letters
Volume	17
Issue number	4
DOIs	https://doi.org/10.1021/acs.nanolett.7b00317
State	Published - Apr 12 2017

Funding

We thank Marco Salluzzo, Thorsten Schmitt, Christophe Berthod, Ulrike Diebold, Martin Setvin, and Anna Tamai for helpful discussions. Experiments were conducted at the Surface/Interface Spectroscopy (SIS) beamline of the Swiss Light Source within the Paul Scherrer Institut in Villigen, Switzerland. Z.Z was supported by the Alexander von Humboldt fellowship. S.M.W., F.Y.B., and F.B. were supported by the Swiss National Science Foundation (Grant 200021- 146995). G.S. was supported by the DFG through SFB 1170 “ToCoTronics.” The contribution by GE was sponsored by the Materials Sciences and Engineering Division, Basic Energy Sciences, Office of Science, U.S. Department of Energy.

Keywords

Titanium dioxide
angle-resolved photoemission spectroscopy
lateral patterning
surface reconstruction
two-dimensional electron liquid

Access to Document

10.1021/acs.nanolett.7b00317

Cite this

Wang, Z., Zhong, Z., McKeown Walker, S., Ristic, Z., Ma, J. Z., Bruno, F. Y., Riccò, S., Sangiovanni, G., Eres, G., Plumb, N. C., Patthey, L., Shi, M., Mesot, J., Baumberger, F., & Radovic, M. (2017). Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO₂ Thin Films. Nano Letters, 17(4), 2561-2567. https://doi.org/10.1021/acs.nanolett.7b00317

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abstract = "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 × 4) in-plane surface reconstruction. Employing photostimulated 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 × 4) surface reconstruction provides a periodic lateral perturbation of the electron liquid. 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.",

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Wang, Z, Zhong, Z, McKeown Walker, S, Ristic, Z, Ma, JZ, Bruno, FY, Riccò, S, Sangiovanni, G, Eres, G, Plumb, NC, Patthey, L, Shi, M, Mesot, J, Baumberger, F & Radovic, M 2017, 'Atomically Precise Lateral Modulation of a Two-Dimensional Electron Liquid in Anatase TiO₂ Thin Films', Nano Letters, vol. 17, no. 4, pp. 2561-2567. https://doi.org/10.1021/acs.nanolett.7b00317

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