Title: Excitonic topological order in electron-hole bilayers

Speaker: Prof. Rui Wang, Nanjing University

Time&Location: 12:00 pm, Oct. 24,  Room B501, Tangzhongying Building 

Abstract:

Topological orders, characterized by long-range quantum entanglement and emergent gauge field, exhibit rich quantum phenomena. Typical examples include the fractional quantum Hall states and the quantum spin liquids, which have been extensively studied over the last decades. However, there are a few open questions yet to be addressed, for example, whether topological orders can be realized in other physical platforms, and is there a universal mechanism for topological orders emergent from correlated systems? Using the Chern-Simons fermionization approach, we show that correlated bosons on a moat band can avoid boson condensation, leading to chiral topological orders mimicking the Kalmeyer-Laughlin chiral spin liquid. We generalize this mechanism to correlated electron-hole systems. We show that the excitons can display strong frustration when the electron-hole have imbalanced densities. The frustration then enhances the quantum fluctuation and suppresses the excitonic condensation, resulting in an excitonic topological order with semionic excitations in the bulk and a chiral excitonic edge state. Finally, based on magneto-transport measurements, we reveal a novel excitonic topological phase in shallowly inverted InAs/GaSb, which provides the experimental evidences of a bosonic chiral topological order formed in electron-hole bilayers.

References：

1. Rui Wang et al., Nature, 619, 57 (2023)

2. Rui Wang et al., Phys. Rev. B 105, 054404 (2022).

3. Rui Wang et al., Phys. Rev. B 106, L121117 (2022).

4. Rui Wang et al., Phys. Rev. B 98, 064402 (2018).

5. Rui Wang et al., Phys. Rev. Lett. 127, 237202 (2021).

Biography: 

Rui Wang received Ph.D. in Physics from Nanjing University in 2017. He then worked as a post doctor at the University of Houston and Shanghai Jiao Tong University till 2019. He joined Nanjing University as a research fellow in 2019 and became an associate professor in 2021. His research interest mainly involves the strongly correlated systems, particularly the novel quantum phenomena driven by the combination of correlation and topology. He has published over 30 peer-reviewed papers in Nature, Nature Communications, PRL, etc. These published works reported the findings in several related fields, including quantum magnetism, quantum spin liquids, and Kondo phenomena in topological baths.