FLEET Chief Investigator A/Prof Lan Wang (RMIT)
Monolayer WTe2 is predicted to be a quantum spin Hall insulator (QSHI) and the quantized edge transport has recently been demonstrated. However, the ‘smoking gun’ signature of a QSHI, spin-momentum locking of the helical edge states, has yet to be experimentally validated. Here, we propose a model and show that the spin quantization axis of the helical edge states in monolayer WTe2 can be precisely determined from the anisotropic magnetoresistance (AMR). After tuning the Fermi level into the band gap, we have experimentally observed that the spin quantization axis of the helical edge states in monolayer WTe2 lies in the plane perpendicular to the current direction with an angle corresponding to the minimum AMR. Our results not only demonstrate that monolayer WTe2 is indeed a QSHI, but also suggest a convenient method to determine the spin quantization axis of other QSHIs.
About the presenter
CI A/Prof Lan Wang (RMIT) leads the Enabling Technology Theme B and also RMIT node leader. Researchers in this theme focuses on realising novel high temperature quantum anomalous Hall systems in Research Theme 1. They utilise two techniques, exfoliating bulk single crystal and CVD synthesis of nanostructures, to synthesise novel 2D materials in Enabling Technologies Theme A.