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We demonstrate that shot noise in Fe/MgO/Fe/MgO/Fe double-barrier magnetic tunnel junctions is determined by the relative magnetic configuration of the junction and also by the asymmetry of the barriers. The proposed theoretical model,…

Mesoscale and Nanoscale Physics · Physics 2012-09-21 J. P. Cascales , D. Herranz , F. G. Aliev , T. Szczepanski , V. K. Dugaev , J. Barnas , A. Duluard , M. Hehn , C. Tiusan

In this study, we propose a spin-star model for spin-(1/2) particles in order to examine the coherence dynamics of a quantum neural network (QNN) unit. Since quantum computing paradigm promises advantages over their classical counterparts,…

Quantum Physics · Physics 2019-05-03 Deniz Türkpençe , Tahir Çetin Akıncı , Serhat Şeker

We show that the tunable hybridization between two lateral quantum dots connected to non-magnetic current leads in a `hanging-dot' configuration that can be used to implement a bipolar spin filter. The competition between Zeeman, exchange…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 F. Mireles , E. Cota , F. Rojas , S. E. Ulloa

We study a Y junction of spin-1/2 Heisenberg chains with an interaction that breaks both time-reversal and chain exchange symmetries, but not their product nor SU(2) symmetry. The boundary phase diagram features a stable disconnected fixed…

Strongly Correlated Electrons · Physics 2019-03-25 F. Buccheri , R. Egger , R. G. Pereira , F. B. Ramos

We develop an analytical theory for generic disorder-driven quantum phase transitions. We apply this formalism to the superconductor-insulator transition and we briefly discuss the applications to the order-disorder transition in quantum…

Superconductivity · Physics 2013-05-29 M. V. Feigel'man , L. B. Ioffe , M. Mézard

We calculate the quantum correction to the classical conductance of a disordered mesoscopic normal-superconducting (NS) junction in which the electron spatial and spin degrees of freedom are coupled by an appreciable spin orbit interaction.…

Condensed Matter · Physics 2009-10-28 Keith Slevin , Jean-Louis Pichard , P. A. Mello

By measuring electron tunneling between a ferromagnet and individual energy levels in an aluminum quantum dot, we show how spin-resolved quantum states can be used as filters to determine spin-dependent tunneling rates. We also observe…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Mandar M. Deshmukh , D. C. Ralph

We use spatial spin separation by a magnetic focusing technique to probe the polarization of quantum point contacts. The point contacts are fabricated from p-type GaAs/AlGaAs heterostructures. A finite polarization is measured in the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 L. P. Rokhinson , L. N. Pfeiffer , K. W. West

We study a two-electron quantum dot molecule in a magnetic field by the direct diagonalization of the Hamiltonian matrix. The ground states of the molecule with the total spin S=0 and S=1 provide a possible realization for a qubit of a…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 A. Harju , S. Siljamäki , R. M. Nieminen

We experimentally study the transport features of electrons in a spin-diode structure consisting of a single semiconductor quantum dot (QD) weakly coupled to one nonmagnetic (NM) and one ferromagnetic (FM) lead, in which the QD has an…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 K. Hamaya , M. Kitabatake , K. Shibata , M. Jung , S. Ishida , T. Taniyama , K. Hirakawa , Y. Arakawa , T. Machida

A most fundamental and longstanding goal in spintronics is to electrically tune highly efficient spin injectors and detectors, preferably compatible with nanoscale electronics. Here, we demonstrate all these points using semiconductor…

Mesoscale and Nanoscale Physics · Physics 2020-08-11 Arunav Bordoloi , Valentina Zannier , Lucia Sorba , Christian Schönenberger , Andreas Baumgartner

We study DC charge and spin transport through a weakly coupled quantum dot, driven by a non-adiabatic periodic change of system parameters. We generalize the model of Tien and Gordon to simultaneously oscillating voltages and tunnel…

Mesoscale and Nanoscale Physics · Physics 2016-01-20 Matthias Braun , Guido Burkard

We show how strongly correlated ultracold bosonic atoms loaded in specific orbital angular momentum states of arrays of cylindrically symmetric potentials can realize a variety of spin-1/2 models of quantum magnetism. We consider explicitly…

Quantum Physics · Physics 2019-08-21 G. Pelegrí , J. Mompart , V. Ahufinger , A. J. Daley

We investigate theoretically the quantum phase transition (QPT) between the one-channel Kondo (1CK) and two-channel Kondo (2CK) fixed points in a quantum dot coupled to helical edge states of interacting 2D topological insulators (2DTI)…

Strongly Correlated Electrons · Physics 2015-06-03 Chung-Hou Chung , Salman Silotri

We develop a theoretical description of transport through quantum dots connected to reservoirs via spin-polarized ballistic contacts. Rate equations account for spin accumulation inside the dot, electron-electron interactions, and…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Eugene G. Mishchenko , Arne Brataas , Yaroslav Tserkovnyak

We discuss the problem of spin-orbit interaction in a 2D chaotic or diffusive quantum dot in the presence of exchange correlations. Spin-orbit scattering breaks spin rotation invariance, and in the crossover regime between different…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Hakan E. Tureci , Y. Alhassid

In this article, we consider fixed spin-1/2 particles interacting through the quantized electromagnetic field in a constant magnetic field. We give approximate evolutions of coherent states. This uses spins-photon classical Hamiltonian…

Analysis of PDEs · Mathematics 2015-12-29 L. Amour , J. Nourrigat

The evolution of the quantum wave packet describing an atom trapped in the surface-tip junction of the scanning tunneling microscope is investigated by using the time-dependent Schroedinger equation, and by a quasi-classical Hamiltonian…

Quantum Physics · Physics 2008-02-21 M. Grigorescu

Manipulation of the spin-states of a quantum dot by purely electrical means is a highly desirable property of fundamental importance for the development of spintronic devices such as spin-filters, spin-transistors and single-spin memory as…

Mesoscale and Nanoscale Physics · Physics 2008-10-20 J. R. Hauptmann , J. Paaske , P. E. Lindelof

We present a dual two dimensional model for the Quantum Hall Fluid depending on two parameters and show that this model has topologically non-trivial vacua which are infrared stable fixed points of the Renormalization Group. The model has a…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 G. Cristofano , D. Giuliano , G. Maiella
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