Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-17298 Wissenschaftlicher Artikel Sánchez, Rafael; Thierschmann, Holger; Molenkamp, Laurens W. Single-electron thermal devices coupled to a mesoscopic gate We theoretically investigate the propagation of heat currents in a three-terminal quantum dot engine. Electron-electron interactions introduce state-dependent processes which can be resolved by energy-dependent tunneling rates. We identify the relevant transitions which define the operation of the system as a thermal transistor or a thermal diode. In the former case, thermal-induced charge fluctuations in the gate dot modify the thermal currents in the conductor with suppressed heat injection, resulting in huge amplification factors and the possible gating with arbitrarily low energy cost. In the latter case, enhanced correlations of the state-selective tunneling transitions redistribute heat flows giving high rectification coefficients and the unexpected cooling of one conductor terminal by heating the other one. We propose quantum dot arrays as a possible way to achieve the extreme tunneling asymmetries required for the different operations. 2017 New Journal of Physics 19 urn:nbn:de:bvb:20-opus-172982 10.1088/1367-2630/aa8b94 Physikalisches Institut OPUS4-12722 Wissenschaftlicher Artikel König, Markus; Baenninger, Matthias; Garcia, Andrei G. F.; Harjee, Nahid; Pruitt, Beth L.; Ames, C.; Leubner, Philipp; Brüne, Christoph; Buhmann, Hartmut; Molenkamp, Laurens W.; Goldhaber-Gordon, David Spatially Resolved Study of Backscattering in the Quantum Spin Hall State The discovery of the quantum spin Hall (QSH) state, and topological insulators in general, has sparked strong experimental efforts. Transport studies of the quantum spin Hall state have confirmed the presence of edge states, showed ballistic edge transport in micron-sized samples, and demonstrated the spin polarization of the helical edge states. While these experiments have confirmed the broad theoretical model, the properties of the QSH edge states have not yet been investigated on a local scale. Using scanning gate microscopy to perturb the QSH edge states on a submicron scale, we identify well-localized scattering sites which likely limit the expected nondissipative transport in the helical edge channels. In the micron-sized regions between the scattering sites, the edge states appear to propagate unperturbed, as expected for an ideal QSH system, and are found to be robust against weak induced potential fluctuations. 2013 21003 Physical Review X 3 2 urn:nbn:de:bvb:20-opus-127225 10.1103/PhysRevX.3.021003 Physikalisches Institut OPUS4-12983 Wissenschaftlicher Artikel Oostinga, Jeroen B.; Maier, Luis; Schüffelgen, Peter; Knott, Daniel; Ames, Christopher; Brüne, Christoph; Tkachov, Grigory; Buhmann, Hartmut; Molenkamp, Laurens W. Josephson Supercurrent through the Topological Surface States of Strained Bulk HgTe Strained bulk HgTe is a three-dimensional topological insulator, whose surface electrons have a high mobility (~ 30 000 cm\(^2\)=Vs), while its bulk is effectively free of mobile charge carriers. These properties enable a study of transport through its unconventional surface states without being hindered by a parallel bulk conductance. Here, we show transport experiments on HgTe-based Josephson junctions to investigate the appearance of the predicted Majorana states at the interface between a topological insulator and a superconductor. Interestingly, we observe a dissipationless supercurrent flow through the topological surface states of HgTe. The current-voltage characteristics are hysteretic at temperatures below 1 K, with critical supercurrents of several microamperes. Moreover, we observe a magnetic-field-induced Fraunhofer pattern of the critical supercurrent, indicating a dominant \(2\pi\)-periodic Josephson effect in the unconventional surface states. Our results show that strained bulk HgTe is a promising material system to get a better understanding of the Josephson effect in topological surface states, and to search for the manifestation of zero-energy Majorana states in transport experiments. 2013 Physical Review X 3 021007 urn:nbn:de:bvb:20-opus-129834 10.1103/PhysRevX.3.021007 Physikalisches Institut OPUS4-11809 Wissenschaftlicher Artikel Brüne, Christoph; Thienel, Cornelius; Stuiber, Michael; Böttcher, Jan; Buhmann, Hartmut; Novik, Elena G.; Liu, Chao-Xing; Hankiewicz, Ewelina M.; Molenkamp, Laurens W. Dirac-Screening Stabilized Surface-State Transport in a Topological Insulator We report magnetotransport studies on a gated strained HgTe device. This material is a three-dimensional topological insulator and exclusively shows surface-state transport. Remarkably, the Landau-level dispersion and the accuracy of the Hall quantization remain unchanged over a wide density range (3×1011  cm−2