Publications (44)
How to measure the entropy of a mesoscopic system via thermoelectric transport
Yaakov Kleeorin, Holger Thierschmann, Hartmut Buhmann +3
Entropy is a fundamental thermodynamic quantity indicative of the accessible degrees of freedom in a system. While it has been suggested that the entropy of a mesoscopic system can…
-periodic Josephson supercurrent in HgTe-based topological Josephson junctions
Jonas Wiedenmann, Erwann Bocquillon, Russell S. Deacon +12
The Josephson effect describes the generic appearance of a supercurrent in a weak link between two superconductors. Its exact physical nature however deeply influences the properti…
Three-Terminal Energy Harvester with Coupled Quantum Dots
Holger Thierschmann, Rafael Sánchez, Björn Sothmann +5
Rectification of thermal fluctuations in mesoscopic conductors is the key idea of today's attempts to build nanoscale thermoelectric energy harvesters in order to convert heat into…
Microwave studies of the fractional Josephson effect in HgTe-based Josephson junctions
Erwann Bocquillon, Jonas Wiedenmann, Russell S. Deacon +3
The rise of topological phases of matter is strongly connected to their potential to host Majorana bound states, a powerful ingredient in the search for a robust, topologically pro…
Nonlinear planar magnetotransport due to tilted Dirac cones in topological materials
Arya Thenapparambil, Graciely Elias dos Santos, Chang-An Li +7
Nonlinear planar magnetotransport is ubiquitous in topological HgTe structures, both in tensile (topological insulator) or compressively strained layers (Weyl semimetal phase). We…
Massive and topological surface states in tensile strained HgTe
David M. Mahler, Valentin L. Müller, Cornelius Thienel +4
Magneto-transport measurements on gated high mobility heterostructures containing a 60 nm layer of tensile strained HgTe, a three-dimensional topological insulator, show well-devel…
kdotpy: theory on a lattice for simulating semiconductor band structures
Wouter Beugeling, Florian Bayer, Christian Berger +11
The software project kdotpy provides a Python application for simulating electronic band structures of semiconductor devices with theory on a lattice. T…
Dirac-screening stabilized surface-state transport in a topological insulator
Christoph Brüne, Cornelius Thienel, Michael Stuiber +6
We report magnetotransport studies on a gated strained HgTe device. This material is a threedimensional topological insulator and exclusively shows surface state transport. Remarka…
The Quantum Spin Hall Effect: Theory and Experiment
Markus Koenig, Hartmut Buhmann, Laurens W. Molenkamp +4
The search for topologically non-trivial states of matter has become an important goal for condensed matter physics. Recently, a new class of topological insulators has been propos…
Josephson radiation from gapless Andreev bound states in HgTe-based topological junctions
Russell S. Deacon, Jonas Wiedenmann, Erwann Bocquillon +9
Frequency analysis of the rf emission of oscillating Josephson supercurrent is a powerful passive way of probing properties of topological Josephson junctions. In particular, measu…
Induced Superconductivity in the Quantum Spin Hall Edge
Sean Hart, Hechen Ren, Timo Wagner +6
Topological insulators are a newly discovered phase of matter characterized by a gapped bulk surrounded by novel conducting boundary states. Since their theoretical discovery, thes…
Unexpected edge conduction in HgTe quantum wells under broken time reversal symmetry
Eric Yue Ma, M. Reyes Calvo, Jing Wang +16
The realization of quantum spin Hall (QSH) effect in HgTe quantum wells (QWs) is considered a milestone in the discovery of topological insulators. The QSH edge states are predicte…
Surface state charge dynamics of a high-mobility three dimensional topological insulator
Jason N. Hancock, J. L. M. van Mechelen, Alexey B. Kuzmenko +6
We present a magneto-optical study of the three-dimensional topological insulator, strained HgTe using a technique which capitalizes on advantages of time-domain spectroscopy to am…
Self-Consistent Model for Gate Control of Narrow-, Broken-, and Inverted-Gap (Topological) Heterostructures
Maximilian Hofer, Christopher Fuchs, Moritz Siebert +8
Even small electrostatic potentials can dramatically influence the band structure of narrow-, broken-, and inverted-gap materials. A quantitative understanding often necessitates a…
Proximity Induced Superconductivity in CdTe-HgTe Core-Shell Nanowires
Jan Hajer, Maximilian Kessel, Christoph Brüne +3
In this letter we report on proximity superconductivity induced in CdTe-HgTe core-shell nanowires, a quasi-one-dimensional heterostructure of the topological insulator HgTe. We dem…
Dynamical separation of bulk and edge transport in HgTe-based 2D topological insulators
Matthieu C. Dartiailh, Simon Hartinger, Alexandre Gourmelon +11
Topological effects in edge states are clearly visible on short lengths only, thus largely impeding their studies. On larger distances, one may be able to dynamically enhance topol…
Thermoelectrics with Coulomb coupled quantum dots
Holger Thierschmann, Rafael Sánchez, Björn Sothmann +2
In this article we review the thermoelectric properties of three terminal devices with Coulomb coupled quantum dots (QDs) as observed in recent experiments [1,2]. The system we con…
Interacting topological edge channels
Jonas Strunz, Jonas Wiedenmann, Christoph Fleckenstein +10
Electrical currents in a quantum spin Hall insulator are confined to the boundary of the system. The charge carriers can be described as massless relativistic particles, whose spin…
Spin polarization of the quantum spin Hall edge states
Christoph Brüne, Andreas Roth, Hartmut Buhmann +5
While the helical character of the edge channels responsible for charge transport in the quantum spin Hall regime of a two-dimensional topological insulator is by now well establis…
Wiedemann-Franz behavior at the Weyl points in compressively strained HgTe
Abu Alex Aravindnath, Yi-Ju Ho, Fabian Schmitt +6
Weyl semimetals, with their unique electronic band structure, have drawn significant interest for their potential to explore quantum anomalies in condensed matter systems. In this…
Electron-hole scattering limited transport of Dirac fermions in a topological insulator
Valentin L. Müller, Yuan Yan, Oleksiy Kashuba +6
We experimentally investigate the effect of electron temperature on transport in the two-dimensional Dirac surface states of the three-dimensional topological insulator HgTe. We fi…
Highly efficient broadband THz upconversion with Dirac materials
Tatiana A. Uaman Svetikova, Igor Ilyakov, Alexey Ponomaryov +16
The use of the THz frequency domain in future network generations offers an unparalleled level of capacity, which can enhance innovative applications in wireless communication, ana…
Topological band inversion in HgTe(001): surface and bulk signatures from photoemission
Raphael C. Vidal, Giovanni Marini, Lukas Lunczer +14
HgTe is a versatile topological material and has enabled the realization of a variety of topological states, including two- and three-dimensional (3D) topological insulators and to…
Counterpropagating topological and quantum Hall edge channels
Saquib Shamim, Pragya Shekhar, Wouter Beugeling +7
The survival of the quantum spin Hall edge channels in presence of an external magnetic field has been a subject of experimental and theoretical research. The inversion of Landau l…
Velocity and confinement of edge plasmons in HgTe-based 2D topological insulators
Alexandre Gourmelon, Elric Frigerio, Hiroshi Kamata +10
High-frequency transport in the edge states of the quantum spin Hall (QSH) effect has to date rarely been explored, though it could cast light on the scattering mechanisms taking p…
Phase-sensitive SQUIDs based on the 3D topological insulator HgTe
Luis Maier, Erwann Bocquillon, Manuel Grimm +6
Three-dimensional topological insulators represent a new class of materials in which transport is governed by Dirac surface states while the bulk remains insulating. Due to helical…
Transport spectroscopy of induced superconductivity in the three-dimensional topological insulator HgTe
Jonas Wiedenmann, Eva Liebhaber, Johannes Kübert +6
The proximity-induced superconducting state in the 3-dimensional topological insulator HgTe has been studied using electronic transport of a normal metal-superconducting point cont…
Room temperature electrically tunable broadband terahertz Faraday effect
Alexey Shuvaev, Andrei Pimenov, Georgy V. Astakhov +4
The terahertz (THz) frequency range (0.1-10 THz) fills the gap between the microwave and optical parts of the electromagnetic spectrum. Recent progress in the generation and detect…
Spectral asymmetry induces a re-entrant quantum Hall effect in a topological insulator
Li-Xian Wang, Wouter Beugeling, Fabian Schmitt +5
The band inversion of topological materials in three spatial dimensions is intimately connected to the parity anomaly of two-dimensional massless Dirac fermions. At finite magnetic…
Non-sinusoidal current-phase relationship in Josephson junctions from the 3D topological insulator HgTe
Ilya Sochnikov, Luis Maier, Christopher A. Watson +8
We use Superconducting QUantum Interference Device (SQUID) microscopy to characterize the current-phase relation (CPR) of Josephson Junctions from 3-dimentional topological insulat…
Josephson supercurrent through the topological surface states of strained bulk HgTe
Jeroen B. Oostinga, Luis Maier, Peter Schueffelgen +6
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…
Spatially resolved study of backscattering in the quantum spin Hall state
Markus König, Matthias Baenninger, Andrei G. F. Garcia +8
The discovery of the Quantum Spin Hall state, and topological insulators in general, has sparked strong experimental efforts. Transport studies of the Quantum Spin Hall state confi…
Interplay of Dirac nodes and Volkov-Pankratov surface states in compressively strained HgTe
David M. Mahler, Julian-Benedikt Mayer, Philipp Leubner +8
Preceded by the discovery of topological insulators, Dirac and Weyl semimetals have become a pivotal direction of research in contemporary condensed matter physics. While easily ac…
Strain Engineering of the Band Gap of HgTe Quantum Wells using Superlattice Virtual Substrates
Philipp Leubner, Lukas Lunczer, Christoph Brüne +2
The HgTe quantum well (QW) is a well-characterized two-dimensional topological insulator (2D-TI). Its band gap is relatively small (typically on the order of 10 meV), which restric…
Emergent quantum Hall effects below mT in a two-dimensional topological insulator
Saquib Shamim, Wouter Beugeling, Jan Böttcher +7
The realization of the quantum spin Hall effect in HgTe quantum wells has led to the development of topological materials which, in combination with magnetism and superconductivity…
Imaging currents in HgTe quantum wells in the quantum spin Hall regime
Katja C. Nowack, Eric M. Spanton, Matthias Baenninger +10
The quantum spin Hall (QSH) state is a genuinely new state of matter characterized by a non-trivial topology of its band structure. Its key feature is conducting edge channels whos…
Quantum Spin Hall Insulator State in HgTe Quantum Wells
Markus Koenig, Steffen Wiedmann, Christoph Bruene +5
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…
Induced superconductivity in the three-dimensional topological insulator HgTe
Luis Maier, Jeroen B. Oostinga, Daniel Knott +7
A strained and undoped HgTe layer is a three-dimensional topological insulator, in which electronic transport occurs dominantly through its surface states. In this Letter, we prese…
Period-doubling in the phase dynamics of a shunted HgTe quantum well Josephson junction
Wei Liu, Stanislau U. Piatrusha, Xianhu Liang +7
The fractional AC Josephson effect is a discerning property of topological superconductivity in hybrid Josephson junctions. Recent experimental observations of missing odd Shapiro…
Temperature-driven transition from a semiconductor to a topological insulator
Steffen Wiedmann, Andreas Jost, Cornelius Thienel +6
We report on a temperature-induced transition from a conventional semiconductor to a two-dimensional topological insulator investigated by means of magnetotransport experiments on…
Controlled Finite Momentum Pairing and Spatially Varying Order Parameter in Proximitized HgTe Quantum Wells
Sean Hart, Hechen Ren, Michael Kosowsky +7
Conventional -wave superconductivity is understood to arise from singlet pairing of electrons with opposite Fermi momenta, forming Cooper pairs whose net momentum is zero [1]. S…
Nonlocal edge state transport in the quantum spin Hall state
Andreas Roth, Christoph Bruene, Hartmut Buhmann +4
We present direct experimental evidence for nonlocal transport in HgTe quantum wells in the quantum spin Hall regime, in the absence of any external magnetic field. The data conclu…
Thermal Gating of Charge Currents with Coulomb Coupled Quantum Dots
Holger Thierschmann, Fabian Arnold, Marcel Mittermüller +5
We have observed thermal gating, i.e. electrostatic gating induced by hot electrons. The effect occurs in a device consisting of two capacitively coupled quantum dots. The double d…
Overlapping Top Gate Electrodes based on Low Temperature Atomic Layer Deposition for Nanoscale Ambipolar Lateral Junctions
Christopher Fuchs, Lena Fürst, Hartmut Buhmann +2
We present overlapping top gate electrodes for the formation of gate defined lateral junctions in semiconducting layers as an alternative to the back gate/top gate combination and…