Terahertz resistive response of a two-dimensional topological insulator in a quasiballistic transport regime

Elastic backscattering of edge electrons and light absorption on a smooth edge of a 2D topological insulator

“…The edge state light absorption was theoretically and experimentally investigated. Theoretically [15,16,19], direct transitions between linear edge state branches should be forbidden by the topological protection, while, in the experiment [6,25,26], this is not the case. Besides, the circular photogalvanic effect in a TI layer was predicted [19].…”

AC Response of the Edge States in a Two‐Dimensional Topological Insulator Coupled to a Conducting Puddle

“…In low-temperature experiments on Au and Cu, the spin-flip time was ≈ 0.1 ns 21 . To the best of our knowledge, so far the ac response in 2D topological insulators was measured at a constant frequency of 2.5 THz and for several-micron long samples 22 , which is marginal for testing the obtained results. One could extend the frequency limits for observing the predicted effects by choosing a shorter distance between the measuring probes and making an artificial puddle between them by approaching a charged STM tip or by selective doping.…”

Microwave Photoresistance of a Two-Dimensional Topological Insulator in a HgTe Quantum Well

“…A two-dimensional topological insulator in a HgTe quantum well with an inverted spectrum is the most reliable experimental implementation of a two-dimensional topological insulator; for this reason, it has been actively studied for more than a decade. A number of phenomena in it from transport and noise phenomena [1][2][3][4][5][6][7] to photoelectric phenomena such as a photogalvanic effect induced by the appearance of chiral spin photocurrents and a terahertz photoresistance caused by optical transitions between helical edge states [8,9] have already been studied.…”

“…They were fabricated on the basis of 8 to 8.5 nm thick HgTe quantum wells, where an inverse energy spectrum is implemented. The structures were described in detail in [9]. The samples were irradiated by microwave radiation in the frequency range of 110-169 GHz through a waveguide.…”