For a stripe geometry device with Fermi energy ε_F = 7 meV, and M = −10 meV. (a) Typical energy spectrum for a HgTe/CdTe quantum well strip in the QSHE region. (b) The conductance G versus disorder strength W in a two-terminal device. The Fermi energy is located inside the inverted gap. (c) Schematic of helical edge states propagation in the boundary of sample. On a given edge, the carriers with opposite spin polarizations propagate in opposite directions. (d)–(f) Configurations of the local current flow vector in a device with central region size L_x = 200a, L_y = 80a under disorder strength (d) W = 0, (e) W = 110 meV, and (f) W = 220 meV. The inset of panel (d) is the schematic of local current flow vector. The direction and length of the arrows represent the local current direction and magnitude. The order of magnitude of the local currents are displayed in the color bar. Adapted from Ref. [32]