Figure 1 : THz magnetooptics of a strained HgTe 3D TI.

From: Observation of the universal magnetoelectric effect in a 3D topological insulator

Figure 1

(a) A scheme of the experimental set-up (only one arm of the Mach–Zehnder interferometer is shown). The strained HgTe layer, which is a 3D TI, is sandwiched between (Cd,Hg)Te protecting layers. The top-gate electrode, consisting of a SiO2/Si3N4 multilayer insulator and a thin conducting Ru film, is semitransparent at THz frequencies. The THz radiation (v=0.35 THz) is linearly polarized, and the Faraday rotation (θF) and ellipticity (ηF) are measured as a function of the magnetic field strength B for different gate voltages UG. (b,c) Transmission spectra in the parallel and crossed polarizer configurations, respectively. The gate voltage is colour-coded, and the experimental curves are shifted for clarity. Notations in b,c: e denotes the CR of the topological surface states of electron character, s1 and s2 denote extra resonances with opposite phase to that of the e-CR as discussed in the text.