Electronic‐Reconstruction‐Enhanced Tunneling Conductance at Terrace Edges of Ultrathin Oxide Films |
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Authors: | Lingfei Wang Rokyeon Kim Yoonkoo Kim Choong H Kim Sangwoon Hwang Myung Rae Cho Yeong Jae Shin Saikat Das Jeong Rae Kim Sergei V Kalinin Miyoung Kim Sang Mo Yang Tae Won Noh |
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Affiliation: | 1. Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, Republic of Korea;2. Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea;3. Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea;4. Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA;5. Department of Physics, Sookmyung Women's University, Seoul, Republic of Korea |
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Abstract: | Quantum mechanical tunneling of electrons across ultrathin insulating oxide barriers has been studied extensively for decades due to its great potential in electronic‐device applications. In the few‐nanometers‐thick epitaxial oxide films, atomic‐scale structural imperfections, such as the ubiquitously existed one‐unit‐cell‐high terrace edges, can dramatically affect the tunneling probability and device performance. However, the underlying physics has not been investigated adequately. Here, taking ultrathin BaTiO3 films as a model system, an intrinsic tunneling‐conductance enhancement is reported near the terrace edges. Scanning‐probe‐microscopy results demonstrate the existence of highly conductive regions (tens of nanometers wide) near the terrace edges. First‐principles calculations suggest that the terrace‐edge geometry can trigger an electronic reconstruction, which reduces the effective tunneling barrier width locally. Furthermore, such tunneling‐conductance enhancement can be discovered in other transition metal oxides and controlled by surface‐termination engineering. The controllable electronic reconstruction can facilitate the implementation of oxide electronic devices and discovery of exotic low‐dimensional quantum phases. |
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Keywords: | electronic reconstruction ferroelectricity quantum tunneling terrace edges ultrathin oxide films |
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