Nanoscale Conductivity Imaging of Correlated Electronic States in WSe_{2}/WS_{2} Moiré Superlattices

Zhaodong Chu; Emma C Regan; Xuejian Ma; Danqing Wang; Zifan Xu; M Iqbal Bakti Utama; Kentaro Yumigeta; Mark Blei; Kenji Watanabe; Takashi Taniguchi; Sefaattin Tongay; Feng Wang; Keji Lai

doi:10.1103/PhysRevLett.125.186803

Nanoscale Conductivity Imaging of Correlated Electronic States in WSe_{2}/WS_{2} Moiré Superlattices

Phys Rev Lett. 2020 Oct 30;125(18):186803. doi: 10.1103/PhysRevLett.125.186803.

Authors

Zhaodong Chu¹, Emma C Regan^{2

3

4}, Xuejian Ma¹, Danqing Wang^{2

3

4}, Zifan Xu¹, M Iqbal Bakti Utama^{2

4

5}, Kentaro Yumigeta⁶, Mark Blei⁶, Kenji Watanabe⁷, Takashi Taniguchi⁸, Sefaattin Tongay⁶, Feng Wang^{2

4

9}, Keji Lai¹

Affiliations

¹ Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA.
² Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
³ Graduate Group in Applied Science and Technology, University of California at Berkeley, Berkeley, California 94720, USA.
⁴ Material Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
⁵ Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720, USA.
⁶ School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, USA.
⁷ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁸ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan.
⁹ Kavli Energy NanoSciences Institute at University of California Berkeley and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

PMID: 33196228
DOI: 10.1103/PhysRevLett.125.186803

Abstract

We report the nanoscale conductivity imaging of correlated electronic states in angle-aligned WSe_{2}/WS_{2} heterostructures using microwave impedance microscopy. The noncontact microwave probe allows us to observe the Mott insulating state with one hole per moiré unit cell that persists for temperatures up to 150 K, consistent with other characterization techniques. In addition, we identify for the first time a Mott insulating state at one electron per moiré unit cell. Appreciable inhomogeneity of the correlated states is directly visualized in the heterobilayer region, indicative of local disorders in the moiré superlattice potential or electrostatic doping. Our work provides important insights on 2D moiré systems down to the microscopic level.