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The amount of heat an integer quantum Hall edge state can carry in equilibrium is quantized in universal units of the heat flux quantum $J_q= \frac{\pi k_B^2}{12 \hbar}T^2$ per edge state. We adress the question of how heat transport in…

Mesoscale and Nanoscale Physics · Physics 2023-01-18 Florian Stäbler , Eugene Sukhorukov

We have investigated low-temperature electronic transport on InAs/GaSb double quantum wells, a system which promises to be electrically tunable from a normal to a topological insulator. Hall bars of $50\,\mu$m in length down to a few $\mu$m…

We propose a topological understanding of the quantum spin Hall state without considering any symmetries, and it follows from the gauge invariance that either the energy gap or the spin spectrum gap needs to close on the system edges, the…

Mesoscale and Nanoscale Physics · Physics 2012-07-09 Huichao Li , L. Sheng , D. Y. Xing

The Quantum Spin Hall insulator is characterized by the presence of gapless helical edge states where the spin of the charge carriers is locked to their direction of motion. In order to probe the properties of the edge modes, we propose a…

Strongly Correlated Electrons · Physics 2013-01-14 Roni Ilan , Jérôme Cayssol , Jens H. Bardarson , Joel E. Moore

We analyze thermally induced spin and charge transport in HgTe/CdTe quantum wells on the basis of the numerical non-equilibrium Green's function technique in the linear response regime. In the topologically non-trivial regime, we find a…

Mesoscale and Nanoscale Physics · Physics 2012-10-30 D. G. Rothe , E. M. Hankiewicz , B. Trauzettel , M. Guigou

Heat transport has large potentialities to unveil new physics in mesoscopic systems. A striking illustration is the integer quantum Hall regime, where the robustness of Hall currents limits information accessible from charge transport.…

Mesoscale and Nanoscale Physics · Physics 2011-01-04 C. Altimiras , H. le Sueur , U. Gennser , A. Cavanna , D. Mailly , F. Pierre

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 proposed. These topological insulators have an insulating gap in…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Markus Koenig , Hartmut Buhmann , Laurens W. Molenkamp , Taylor L. Hughes , Chao-Xing Liu , Xiao-Liang Qi , Shou-Cheng Zhang

We study the dynamics of a quantum spin Hall edge coupled to a magnet with its own dynamics. Using spin transfer torque principles, we analyze the interplay between spin currents in the edge state and dynamics of the axis of the magnet, and…

Mesoscale and Nanoscale Physics · Physics 2014-11-11 Qinglei Meng , Smitha Vishveshwara , Taylor L. Hughes

Using the non-equilibrium Green\noindent 's function method and the Keldysh formalism, we study the effects of spin-orbit interactions and time-reversal symmetry breaking exchange fields on non-equilibrium quantum transport in graphene…

Mesoscale and Nanoscale Physics · Physics 2018-07-19 Nezhat Pournaghavi , Cecilia Holmqvist , Anna Pertsova , Carlo Canali

We use the edge of the quantum Hall sample to study the possibility for counter-propagating neutral collective excitations. A novel sample design allows us to independently investigate charge and energy transport along the edge. We…

Mesoscale and Nanoscale Physics · Physics 2015-03-17 E. V. Deviatov , A. Lorke , G. Biasiol , L. Sorba

The quantum spin Hall (QSH) states discovered in an inverted band of InAs/GaSb and HgTe/CdTe quantum wells categorize them among the very superior candidates for topological insulators. In the presence of a magnetic field, these QSH states…

Mesoscale and Nanoscale Physics · Physics 2022-04-04 Alestin Mawrie

We study the edge-channel transport of electrons in a high-mobility Si/SiGe two-dimensional electron system in the quantum Hall regime. By selectively populating the spin-resolved edge channels, we observe suppression of the scattering…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 K. Hamaya , S. Masubuchi , K. Hirakawa , S. Ishida , Y. Arakawa , K. Sawano , Y. Shiraki , T. Machida

The spin Hall effect in a two-dimensional electron system on honeycomb lattice with both intrinsic and Rashba spin-orbit couplings is studied numerically. Integer quantized spin Hall conductance is obtained at zero Rashba coupling limit…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 L. Sheng , D. N. Sheng , C. S. Ting , F. D. M. Haldane

We predict by first-principles calculations that thin films of Cr-doped (Bi,Sb)$_2$Te$_3$ magnetic topological insulator have gapless non-chiral edge states coexisting with the chiral edge state. Such gapless non-chiral states are not…

Mesoscale and Nanoscale Physics · Physics 2013-08-22 Jing Wang , Biao Lian , Haijun Zhang , Shou-Cheng Zhang

We theoretically investigate electrical transport in a quantum Hall system hosting bulk and edge current carrying states. Spatially varying magnetic and electric confinement creates pairs of current carrying lines that drift in the same or…

Mesoscale and Nanoscale Physics · Physics 2018-09-12 Puja Mondal , Alain Nogaret , Sankalpa Ghosh

We develop a theory of edge state transport in separately contacted double-layer quantum Hall systems which are tuned close to the resonance condition for tunneling between the layers. When applied to the case where contact is made to only…

Condensed Matter · Physics 2009-10-28 D. Yoshioka , A. H. MacDonald

We experimentally study electron transport between edge states in the fractional quantum Hall effect regime. We find an anomalous increase of the transport across the 2/3 incompressible fractional stripe in comparison with theoretical…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 E. V. Deviatov , V. T. Dolgopolov , A. Lorke , W. Wegscheider , A. D. Wieck

We investigate an effective low energy theory of HgTe quantum wells near their mass inversion thickness in a perpendicular magnetic field. By comparison of the effective band structure with a more elaborated and well-established model, the…

Mesoscale and Nanoscale Physics · Physics 2009-06-15 M. J. Schmidt , E. G. Novik , M. Kindermann , B. Trauzettel

We analyze the dynamics of the helical edge modes of a quantum spin Hall state in the presence of a spatially non-uniform Rashba spin-orbit (SO) interaction. A randomly fluctuating Rashba SO coupling is found to open a scattering channel…

Mesoscale and Nanoscale Physics · Physics 2010-07-01 Anders Ström , Henrik Johannesson , G. I. Japaridze

We show that burying of the Dirac point in semiconductor-based quantum-spin-Hall systems can generate unexpected robustness of edge states to magnetic fields. A detailed ${\bf k\cdot p}$ band-structure analysis reveals that InAs/GaSb and…

Mesoscale and Nanoscale Physics · Physics 2018-11-21 Rafal Skolasinski , Dmitry I. Pikulin , Jason Alicea , Michael Wimmer