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Quantum oscillations in a dipolar excitonic insulator.
Phuong X Nguyen1,2, Raghav Chaturvedi1, Bo Zou3
1School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
Nature Materials
|August 25, 2025
Summary
Quantum oscillations were observed in an excitonic insulator, a material not expected to show this behavior. This discovery in electron-hole double layers opens new avenues for studying correlated insulators.
Area of Science:
- Condensed Matter Physics
- Quantum Materials
Background:
- Quantum oscillations in magnetization and resistivity are characteristic of metals in magnetic fields.
- Their observation in insulators, such as Kondo insulators, is unexpected and not well understood.
- Excitonic insulators, a distinct class of correlated insulators, have not been previously studied for quantum oscillations.
Purpose of the Study:
- To investigate quantum oscillations in a tunable excitonic insulator.
- To explore the transition between excitonic insulator and quantum Hall states.
- To understand the role of excitonic correlations in quantum phenomena.
Main Methods:
- Fabrication of a gate-controlled excitonic insulator in Coulomb-coupled electron-hole double layers.
- Measurement of resistivity oscillations as a function of magnetic field and carrier density.
- Compressibility and Coulomb drag measurements to probe excitonic properties.
Main Results:
- Observed distinct resistivity oscillations in the excitonic insulator.
- Identified recurring transitions between excitonic insulator and quantum Hall states.
- Demonstrated oscillatory exciton binding energy and signatures of finite-angular-momentum excitonic correlations.
Conclusions:
- Established a tunable platform for studying quantum oscillations in correlated insulators using electron-hole double layers.
- Provided experimental evidence and theoretical insights into quantum oscillations in excitonic insulators.
- Opened new possibilities for exploring exotic quantum phenomena in engineered correlated systems.
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