This work is supported by the NSF DMR-1708688, by the STC Center for Integrated Quantum Materials under NSF grant number DMR-1231319, and by the NSF GRFP under grant DGE1144152. This work is also partly supported by the US Army Research Office and was accomplished under grant W911NF-18-1-0316. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the US Government. The US Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. A.T.P. is supported by the US Department of Defense through the National Defense Science and Engineering Graduate Fellowship Program. The work at the University of Würzburg is supported by the German Research Foundation (Leibniz Program, Sonderforschungsbereich 1170 ‘ToCoTronics’; Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter, ct.qmat, EXC 2147, project 39085490), the EU ERC-AG programme (Project 4-TOPS) and the Bavarian Ministry of Education, Science and the Arts (IDK Topologische Isolatoren and ITI research initiative).

Reviewer information

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