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A single Co atom adsorbed on Cu(111) or on ferromagnetic Co islands is contacted with non-magnetic W or ferromagnetic Ni tips in a scanning tunneling microscope. When the Co atom bridges two non-magnetic electrodes conductances of 2e^2/h…

Materials Science · Physics 2009-11-13 N. Neel , J. Kroeger , R. Berndt

Very short quantum wires (quantum contacts) exhibit a conductance structure at the value of conductance close to 0.7 x 2e^2/h. The structure was discovered by Thomas et al (Phys. Rev. Lett. {\bf 77}, 135 (1996)). Dependence of the structure…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 O. P. Sushkov

We present a first-principles investigation to show that the contact conductance of a half conductance quantum ($G_0/2$) found previously does not generally hold for single-atom magnetic junctions composed of a tip and an adatom dsorbed on…

Mesoscale and Nanoscale Physics · Physics 2013-06-17 Yi-qun Xie , Qiang Li , Lei Huang , Xiang Ye , San-Huang Ke

Since the ground-breaking discovery of the quantum Hall effect, half-quantized quantum Hall plateaus have been some of the most studied and sought-after states. Their importance stems not only from the fact that they transcend the composite…

We show that partially separated Andreev bound states (ps-ABSs), comprised of pairs of overlapping Majorana bound states (MBSs) emerging in quantum dot-semiconductor-superconductor heterostructures, produce robust zero bias conductance…

Mesoscale and Nanoscale Physics · Physics 2018-10-24 C. Moore , Chuanchang Zeng , T. D. Stanescu , Sumanta Tewari

We investigated the effect due to perpendicular magnetic field on quantum wires where spin-orbit interaction (SOI) of electrons is not neglected. Based on the calculated energy dispersion, the nonlinear ballistic conductance ($G$) and…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Godfrey Gumbs , Antonios Balassis , Danhong Huang , Sheehan Ahmed , Ryan Brennan

Clean one-dimensional electron systems can exhibit quantized conductance. The plateau conductance doubles if the transport is dominated by Andreev reflection. Here, we report quantized conductance observed in both Andreev and normal-state…

We model the 2-probe conductance of a quantum point contact (QPC), in linear response. If the QPC is highly non-adiabatic or near to scatterers in the open reservoir regions, then the usual distinction between leads and reservoirs breaks…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 A. H. Barnett , M. Blaauboer , A. Mody , E. J. Heller

The unexpected "0.7" plateau of conductance quantisation is usually observed for ballistic one-dimensional devices. In this work we study a quasi-ballistic quantum wire, for which the disorder induced backscattering reduces the conductance…

Mesoscale and Nanoscale Physics · Physics 2009-03-24 M. Czapkiewicz , P. Zagrajek , J. Wrobel , G. Grabecki , K. Fronc , T. Dietl , Y. Ono , S. Matsuzaka , H. Ohno

Thermoelectric transport coefficients are determined for semiconductor quantum wires with weak thickness fluctuations. Such systems exhibit anomalies in conductance near 1/4 and 3/4 of 2e^2/h on the rising edge to the first conductance…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 T. Rejec , A. Ramsak , J. H. Jefferson

Atomic-sized lead (Pb) contacts are deposited and dissolved in an electrochemical environment, and their transport properties are measured. Due to the electrochemical fabrication process, we obtain mechanically unstrained contacts and…

Mesoscale and Nanoscale Physics · Physics 2010-09-21 F. -Q. Xie , F. Hüser , F. Pauly , Ch. Obermair , G. Schön , Th. Schimmel

Edge reconstruction of gate-tunable compressible quantum Hall fluids in the filling fraction range 1/3 to 2/3 is studied by measuring transmitted conductance of two individually excited fractional $e^2/3h$ edge modes of bulk 2/3 fractional…

We use the technique of bosonization to understand a variety of recent experimental results on the conductivity of a quantum wire. The quantum wire is taken to be a finite-length Luttinger liquid connected on two sides to semi-infinite…

Strongly Correlated Electrons · Physics 2009-11-07 Siddhartha Lal , Sumathi Rao , Diptiman Sen

Ground-state properties of a double-large-dot sample connected to a reservoir via a single-mode point contact are investigated. When the interdot transmission is perfect and the dots controlled by the same dimensionless gate voltage, we…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Karyn Le Hur

We propose that two-channel orbital Kondo ``spin'' 1/2 conductance can be measured in a quantum dot at Coulomb Blockade with an odd number of electrons with contacts in a pillar configuration, if an orthogonal magnetic field induces an…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Domenico Giuliano , Benoit Jouault , Arturo Tagliacozzo

Quantized conductance in quasi-one-dimensional systems not only provides a hallmark of ballistic transport, but also serves as a gateway for exploring quantum phenomena. Recently, a unique hidden Rashba effect attracts tremendous attention,…

We measure electron transport through point contacts in an electron gas in AlGaAs/GaAs heterostructures and graphene for a range of temperatures, magnetic fields and electron densities. We find a magnetoconductance peak around B = 0. With…

Gate-tunable high-mobility InSb/In_{1-x}Al_{x}Sb quantum wells (QWs) grown on GaAs substrates are reported. The QW two-dimensional electron gas (2DEG) channel mobility in excess of 200,000 cm^{2}/Vs is measured at T=1.8K. In asymmetrically…

We report an experimental study on the shot noise as well as the dc transport properties of a quantum point contact (QPC) whose conductance anomaly can be tuned electrostatically by the gate electrodes. By controlling the single QPC so that…

Mesoscale and Nanoscale Physics · Physics 2009-06-08 Shuji Nakamura , Masayuki Hashisaka , Yoshiaki Yamauchi , Shinya Kasai , Teruo Ono , Kensuke Kobayashi

We studied theoretically ballistic electronic transport in a proposed mesoscopic structure - Quantum Cable. Our results demonstrated that Qauntum Cable is a unique structure for the study of mesoscopic transport. As a function of Fermi…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Z. Y. Zeng , Y. Xiang , L. D. Zhang