Experimental work at UCSB was supported by the ARO under award MURI W911NF-16-1-0361. D.R. and J.C.H. acknowledge support by the US Department of Energy, DE-SC0016703, for synthesis of WSe 2 crystals. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by the MEXT, Japan, and the CREST (JPMJCR15F3), JST. M.P.Z. was supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division of the US Department of Energy under contract no. DE-AC02-05-CH11231 (van der Waals heterostructures programme, KCWF16). A.F.Y. acknowledges the support of the David and Lucile Packard Foundation and the Alfred. P. Sloan Foundation. J.O.I. acknowledges the support of the Netherlands Organization for Scientific Research (NWO) through the Rubicon grant, project number 680-50-1525/2474. C.L. and L.S.L. acknowledge support of the STC Center for Integrated Quantum Materials under NSF grant no. DMR-1231319. J.Y.K. acknowledges support by the National Science Scholarship from the Agency for Science, Technology and Research (A*STAR). A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by National Science Foundation Cooperative Agreement no. DMR-1644779 and the State of Florida. Measurements made use of a dilution refrigerator funded through the Major Research Instrumentation Program of the US National Science Foundation under award no. DMR-1531389, and the MRL Shared Experimental Facilities, which are supported by the MRSEC Program of the US National Science Foundation under award no. DMR-1720256.

Reviewer information

Nature thanks Saroj Prasad Dash and the other anonymous reviewer(s) for their contribution to the peer review of this work.