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We report on the observation of the quantum Hall effect at high temperatures in HgTe quantum wells with a finite band gap and a thickness below and above the critical thickness $d_textnormal{c}$ that separates a conventional semiconductor from a two-dimensional topological insulator. At high carrier concentrations we observe a quantized Hall conductivity up to 60,K with energy gaps between Landau Levels of the order of 25,meV, in good agreement with the Landau Level spectrum obtained from $mathbf{kcdot p}$-calculations. Using the scaling approach for the plateau-plateau transition at $ u=2rightarrow 1$, we find the scaling coefficient $kappa =0.45 pm 0.04$ to be consistent with the universality of scaling theory and we do not find signs of increased electron-phonon interaction to alter the scaling even at these elevated temperatures. Comparing the high temperature limit of the quantized Hall resistance in HgTe quantum wells with a finite band gap with room temperature experiment in graphene, we find the energy gaps at the break-down of the quantization to exceed the thermal energy by the same order of magnitude.
Magnetotransport measurements are presented on paramagnetic (Hg,Mn)Te quantum wells (QWs) with an inverted band structure. Gate-voltage controlled density dependent measurements reveal an unusual behavior in the transition regime from n- to p-type co
Recent theory predicted that the Quantum Spin Hall Effect, a fundamentally novel quantum state of matter that exists at zero external magnetic field, may be realized in HgTe/(Hg,Cd)Te quantum wells. We have fabricated such sample structures with low
We report on magnetospectroscopy of HgTe quantum wells in magnetic fields up to 45 T in temperature range from 4.2 K up to 185 K. We observe intra- and inter-band transitions from zero-mode Landau levels, which split from the bottom conduction and up
We study the spin-dependent transmission through interfaces between a HgTe/CdTe quantum well (QW) and a metal - both for the normal metal and the superconducting case. Interestingly, we discover a new type of spin Hall effect at these interfaces that
We report on the observation of the terahertz radiation induced circular (CPGE) and linear (LPGE) photogalvanic effects in HgTe quantum wells. The current response is well described by the phenomenological theory of CPGE and LPGE.