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Charge-order-enhanced capacitance in semiconductor moiré superlattices
Tingxin Li1, Jiacheng Zhu1, Yanhao Tang1
1School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
Nature Nanotechnology
|August 24, 2021
Summary
Researchers studied thermodynamic properties of correlated insulating states in Van der Waals moiré materials using gate capacitance measurements. They observed anomalously large capacitance, revealing insights into electronic correlations and enabling property extraction.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanoscience
Background:
- Van der Waals moiré materials offer a tunable platform for investigating electronic correlation phenomena.
- Correlated insulating states have been identified in semiconductor moiré systems at various filling factors.
Purpose of the Study:
- To explore the thermodynamic properties of correlated insulating states in MoSe2/WS2 moiré superlattices.
- To utilize gate capacitance measurements as a probe for understanding these electronic states.
Main Methods:
- Measurement of gate capacitance in MoSe2/WS2 moiré superlattices.
- Analysis of capacitance variations across different filling factors (0-8).
Main Results:
- Observation of incompressible states at integer and fractional filling factors.
- Discovery of anomalously large capacitance (up to 60% above geometrical capacitance) in compressible regions.
- Identification of device-geometry-dependent Coulomb interactions and charge-ordered state phase mixing as the cause of large capacitance.
Conclusions:
- Gate capacitance is established as a powerful technique for probing correlated states in semiconductor moiré systems.
- Thermodynamic properties, including the gap, electronic entropy, and specific heat capacity, were successfully extracted.
- Control over these correlated states can be achieved through sample-gate coupling.
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