Large Enhancement of 2D Electron Gases Mobility Induced by Interfacial Localized Electron Screening Effect |
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| Authors: | Xiao Chi Zhen Huang Teguh C. Asmara Kun Han Xinmao Yin Xiaojiang Yu Caozheng Diao Ming Yang Daniel Schmidt Ping Yang Paolo E. Trevisanutto T. J. Whitcher T. Venkatesan Mark B. H. Breese Ariando Andrivo Rusydi |
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| Affiliation: | 1. Singapore Synchrotron Light Source, National University of Singapore, Singapore, Singapore;2. Department of Physics, National University of Singapore, Singapore, Singapore;3. NUSSNI‐NanoCore, National University of Singapore, Singapore, Singapore;4. Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore;5. Institute of Materials Research and Engineering, Singapore, Singapore;6. National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), Singapore, Singapore;7. Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore |
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| Abstract: | The interactions between delocalized and localized charges play important roles in correlated electron systems. Here, using a combination of transport measurements, spectroscopic ellipsometry (SE), and X‐ray absorption spectroscopy (XAS) supported by theoretical calculations, we reveal the important role of interfacial localized charges and their screening effects in determining the mobility of (La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/SrTiO3) interfaces. When the LSAT layer thickness reaches the critical value of 5 uc, the insulating interface abruptly becomes conducting, accompanied by the appearance of a new midgap state. This midgap state emerges at ≈1 eV below the Ti t2g band and shows a strong character of Ti 3dxy – O 2p hybridization. Increasing the LSAT layer from 5 to 18 uc, the number of localized charges increases, resulting in an enhanced screening effect and higher mobile electron mobility. This observation contradicts the traditional semiconductor interface where the localized charges always suppress the carrier mobility. These results demonstrate a new strategy to probe localized charges and mobile electrons in correlated electronic systems and highlight the important role of screening effects from localized charges in improving the mobile electron mobility at complex oxide interfaces. |
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| Keywords: | 2D electron gases highly interfacial electron mobility oxide heterostructures screening effect X‐ray and optical spectra |
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