Abstract
The strong electron interactions in the minibands formed in moiré superlattices of van der Waals materials, such as twisted graphene and transition metal dichalcogenides, make such systems a fascinating platform with which to study strongly correlated states1–19. In most systems, the correlated states appear when the moiré lattice is filled by an integer number of electrons per moiré unit cell. Recently, correlated states at fractional fillings of 1/3 and 2/3 holes per moiré unit cell have been reported in the WS2/WSe2 hetero-bilayer, hinting at the long-range nature of the electron interaction16. Here we observe a series of correlated insulating states at fractional fillings of the moiré minibands on both electron- and hole-doped sides in angle-aligned WS2/WSe2 hetero-bilayers, with certain states persisting at temperatures up to 120 K. Simulations reveal that these insulating states correspond to ordering of electrons in the moiré lattice with a periodicity much larger than the moiré unit cell, indicating a surprisingly strong and long-range interaction beyond the nearest neighbours.
| Original language | English |
|---|---|
| Pages (from-to) | 715-719 |
| Number of pages | 5 |
| Journal | Nature Physics |
| Volume | 17 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2021 |
Funding
We thank D. Chen, L. Yan, L. Ma and K. Li for help with device fabrication. We are grateful to R. Swendsen and M. Widom for their help with the Monte Carlo simulation. C.W. and D.X. thank W. Duan for providing part of the computational resources. X.H. and Y.-T.C. acknowledge support from the NSF under award no. DMR-2004701, a Hellman Fellowship award and a seed fund from SHINES, an EFRC funded by the US Department of Energy (DOE), Basic Energy Sciences (BES) under award no. SC0012670. S.M., Z. Li and S.-F.S. acknowledge support by AFOSR through grant no. FA9550-18-1-0312. T.W. and S.-F.S. acknowledge support from ACS PRF through grant no. 59957-DNI10. Z. Lian and S.-F.S. acknowledge support from NYSTAR through Focus Center-NY–RPI contract C150117. Device fabrication was supported by the Micro and Nanofabrication Clean Room (MNCR) at Rensselaer Polytechnic Institute (RPI). S.-F.S. also acknowledges support from the NSF through Career grant no. DMR-1945420. The research by S.O. is supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. C.W. and D.X. acknowledge support from DOE, BES grant no. DE-SC0012509. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT (Japan; grant no. JPMXP0112101001), JSPS (KAKENHI grant no. JP20H00354) and the CREST (JPMJCR15F3), JST. We acknowledge computing time provided by BRIDGES at the Pittsburgh Supercomputing Center (award no. TG-DMR190080) under the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF (ACI-1548562).
| Funders | Funder number |
|---|---|
| BRIDGES | |
| EFRC | |
| Pittsburgh Supercomputing Center | TG-DMR190080 |
| National Science Foundation | 1945420, ACI-1548562, 2004701 |
| U.S. Department of Energy | |
| American Cancer Society | |
| Division of Materials Research | DMR-2004701, DMR-1945420 |
| Air Force Office of Scientific Research | FA9550-18-1-0312 |
| Office of Science | |
| Basic Energy Sciences | SC0012670 |
| American Chemical Society Petroleum Research Fund | 59957-DNI10 |
| Empire State Development's Division of Science, Technology and Innovation | C150117 |
| Division of Materials Sciences and Engineering | DE-SC0012509 |
| Japan Society for the Promotion of Science | JP20H00354 |
| Ministry of Education, Culture, Sports, Science and Technology | |
| Japan Science and Technology Agency | JPMXP0112101001 |
| Core Research for Evolutional Science and Technology | JPMJCR15F3 |