Observation of two-dimensional small polarons at the LaAlO<sub>3</sub>/SrTiO<sub>3</sub> interface
ORAL
Abstract
Two-dimensional (2D) perovskite oxide interfaces are condensed-matter systems where intriguing emergent properties can be observed. The onset of polaronic properties at such interfaces is a scientific discipline where both theoretical and experimental investigations can uncover interesting insights pertaining to many-body charge dynamics. Here, we report the direct observation of small-polarons at the LaAlO3/SrTiO3 (LAO/STO) conducting interface using high-resolution spectroscopic ellipsometry. The experimental observations are complemented by first-principles investigations further reveals a strong coupling between the interfacial electrons and the Ti-lattice that results in the formation of localized 2D small polarons. These findings resolve the longstanding issue where the experimentally derived interfacial carrier density is significantly lower than theoretically predicted values.
*This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDB25000000, National Natural Science Foundation (52172271), the National Key R&D Program of China No. 2022YFE03150200.Ministry of Education, Singapore Tier 2 grant (MOE2019-T2-2-30) and computing resource provided by the Centre for Advanced 2D Materials and Graphene Research at National University of Singapore, and National Supercomputing Centre of Singapore.The authors would like to acknowledge the Singapore Synchrotron Light Source for providing the facility necessary for conducting the research. The Laboratory is a National Research Infrastructure under the National Research Foundation, Singapore.
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Presenters
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Chi Sin Tang
- National University of Singapore