Direct imaging of the electron liquid at oxide interfaces. Song, K., Ryu, S., Lee, H., Paudel, T. R., Koch, C. T., Park, B., Lee, J. K., Choi, S., Kim, Y., Kim, J. C., Jeong, H. Y., Rzchowski, M. S., Tsymbal, E. Y., Eom, C., & Oh, S. H. NATURE NANOTECHNOLOGY, 13(3):198+, MAR, 2018.
doi  abstract   bibtex   
The breaking of symmetry across an oxide heterostructure causes the electronic orbitals to be reconstructed at the interface into energy states that are different from their bulk counterparts(1). The detailed nature of the orbital reconstruction critically affects the spatial confinement and the physical properties of the electrons occupying the interfacial orbitals(2-4). Using an example of two-dimensional electron liquids forming at LaAlO3/SrTiO3 interfaces(5,6) with different crystal symmetry, we show that the selective orbital occupation and spatial quantum confinement of electrons can be resolved with subnanometre resolution using inline electron holography. For the standard (001) interface, the charge density map obtained by inline electron holography shows that the two-dimensional electron liquid is confined to the interface with narrow spatial extension (similar to 1.0 +/- 0.3 nm in the half width). On the other hand, the two-dimensional electron liquid formed at the (111) interface shows a much broader spatial extension (similar to 3.3 +/- 0.3 nm) with the maximum density located similar to 2.4 nm away from the interface, in excellent agreement with density functional theory calculations.
@article{ ISI:000427009000011,
Author = {Song, Kyung and Ryu, Sangwoo and Lee, Hyungwoo and Paudel, Tula R. and
   Koch, Christoph T. and Park, Bumsu and Lee, Ja Kyung and Choi, Si-Young
   and Kim, Young-Min and Kim, Jong Chan and Jeong, Hu Young and Rzchowski,
   Mark S. and Tsymbal, Evgeny Y. and Eom, Chang-Beom and Oh, Sang Ho},
Title = {{Direct imaging of the electron liquid at oxide interfaces}},
Journal = {{NATURE NANOTECHNOLOGY}},
Year = {{2018}},
Volume = {{13}},
Number = {{3}},
Pages = {{198+}},
Month = {{MAR}},
Abstract = {{The breaking of symmetry across an oxide heterostructure causes the
   electronic orbitals to be reconstructed at the interface into energy
   states that are different from their bulk counterparts(1). The detailed
   nature of the orbital reconstruction critically affects the spatial
   confinement and the physical properties of the electrons occupying the
   interfacial orbitals(2-4). Using an example of two-dimensional electron
   liquids forming at LaAlO3/SrTiO3 interfaces(5,6) with different crystal
   symmetry, we show that the selective orbital occupation and spatial
   quantum confinement of electrons can be resolved with subnanometre
   resolution using inline electron holography. For the standard (001)
   interface, the charge density map obtained by inline electron holography
   shows that the two-dimensional electron liquid is confined to the
   interface with narrow spatial extension (similar to 1.0 +/- 0.3 nm in
   the half width). On the other hand, the two-dimensional electron liquid
   formed at the (111) interface shows a much broader spatial extension
   (similar to 3.3 +/- 0.3 nm) with the maximum density located similar to
   2.4 nm away from the interface, in excellent agreement with density
   functional theory calculations.}},
DOI = {{10.1038/s41565-017-0040-8}},
ISSN = {{1748-3387}},
EISSN = {{1748-3395}},
ResearcherID-Numbers = {{Kim, Young-Min/B-7338-2012
   Tsymbal, Evgeny/G-3493-2013
   }},
ORCID-Numbers = {{Kim, Young-Min/0000-0003-3220-9004
   Tsymbal, Evgeny/0000-0002-6728-5480
   Park, Bumsu/0000-0003-1052-8848}},
Unique-ID = {{ISI:000427009000011}},
}

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