Spinful hinge states in the higher-order topological insulators WTe2

Multilayer T_d-WTe₂ has a noncentrosymmetric orthorhombic structure belonging to the SG 31 (Pmn2₁) space group with two perpendicular axes (a– and b-axis) and one mirror line along the b-axis (Fig. 1a). Together with the time-reversal symmetry, this spatial mirror symmetry satisfies necessary prerequisites to support the topologically non-trivial spin-polarized helical hinges^26,28. In our experiments, multilayer WTe₂ is placed on monolayer graphene to detect the spinful 1D hinge state by observing the spin polarization of electrons in graphene injected from WTe₂. The experiment schematic…