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Spin currents are key to spin torque devices, but determining the proper spin current is non-trivial. Here we derive a general quantum-mechanical formula for the intrinsic proper spin current showing that it is topological and can be finite…

Mesoscale and Nanoscale Physics · Physics 2024-02-13 Hong Liu , James H. Cullen , Dimitrie Culcer

We propose a quantum interference spin-injector nanodevice consisting of a superconductor-normal metal hybrid loop connected to a superconductor-ferromagnet bilayer via a tunneling junction. We show that for certain values of the applied…

Mesoscale and Nanoscale Physics · Physics 2013-04-25 F. Giazotto , F. S. Bergeret

The large spin orbit coupling in topological insulators results in helical spin-textured Dirac surface states that are attractive for topological spintronics. These states generate an efficient spin-orbit torque on proximal magnetic moments…

Mesoscale and Nanoscale Physics · Physics 2018-02-07 Yang Lv , James Kally , Delin Zhang , Joon Sue Lee , Mahdi Jamali , Nitin Samarth , Jian-Ping Wang

Non-equilibrium spin transport through an interacting quantum dot is analyzed. The coherent spin oscillations in the dot provide a generating source for spin current. In the interacting regime, the Kondo effect is influenced in a…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Ping Zhang , Qi-Kun Xue , X. C. Xie

We demonstrate that spin current can be generated by an ac voltage in a one-channel quantum wire with strong repulsive electron interactions in the presence of a non-magnetic impurity and uniform static magnetic field. In a certain range of…

Mesoscale and Nanoscale Physics · Physics 2007-08-28 Bernd Braunecker , D. E. Feldman , Feifei Li

We report transport measurements in a single edge channel of an InAs/GaSb quantum spin Hall insulator, where the conduction occurs through only one pair of counterpropagating edge modes. By using a specific sample design involving highly…

Mesoscale and Nanoscale Physics · Physics 2016-07-13 François Couëdo , Hiroshi Irie , Kyoichi Suzuki , Koji Onomitsu , Koji Muraki

Electron tunneling through a single magnetic barrier in a HgTe topological insulator has been theoretically investigated. We find that the perpendicular magnetic field would not lead to spin-flip of the edge states due to the conservation…

Mesoscale and Nanoscale Physics · Physics 2016-07-21 L. Lin , X. Wu , W. Low , D. Zhang , Zhenhua Wu

We discuss the possibility to generate, manipulate, and probe single spins in single-level quantum dots coupled to ferromagnetic leads. The spin-polarized currents flowing between dot and leads lead to a non-equilibrium spin accumulation,…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Matthias Braun , Jürgen König , Jan Martinek

We consider the generation of a pure spin-current at zero bias voltage with a single time-dependent potential. To such end we study a device made of a mesoscopic ring connected to electrodes and clarify the interplay between a magnetic…

Mesoscale and Nanoscale Physics · Physics 2014-08-28 J. P. Ramos , L. E. F. Foa Torres , P. A. Orellana , V. M. Apel

Time-reversal symmetry and rotational invariance in spin space characterize usual non-magnetic conductors. These symmetries give rise, at least, to four-fold degenerate multiplets which, by definition, exhibit a null total spin-momentum…

Mesoscale and Nanoscale Physics · Physics 2011-09-23 Manuel Valin-Rodriguez

We consider a three-port single-level quantum dot system with one input and two output leads. Instead of considering an empty dot, we study the situations that two input electrons co-tunnel through the quantum dot occupied by one or two dot…

Quantum Physics · Physics 2007-05-23 Chih-Lung Chou

We propose a spin polarizer device composed of a quantum dot connected to the spin polarized leads. The spin control of the current flowing through the device is entirely due to the Coulomb interactions present inside the dot. We show that…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Piotr Stefanski

We investigate the Kondo effect in the two-dimensional electron system with a non-trivial quadratic energy band crossing point. We show that the Kondo effect can induce a new hybrid topological insulator phase which is a coexistence state…

Strongly Correlated Electrons · Physics 2016-10-04 Rui Wang , Baigeng Wang , L. Sheng , D. Y. Xing , Jian Wang

A quantum dot formed in a suspended carbon nanotube exposed to an external magnetic field is predicted to act as a thermoelectric unipolar spin battery which generates pure spin current. The built-in spin flip mechanism is a consequence of…

Mesoscale and Nanoscale Physics · Physics 2017-03-20 Zhan Cao , Tie-Feng Fang , Wan-Xiu He , Hong-Gang Luo

With gate-defined electrostatic traps fabricated on a double quantum well we are able to realize an optically active and voltage-tunable quantum dot confining individual, long-living, spatially indirect excitons. We study the transition…

Mesoscale and Nanoscale Physics · Physics 2012-04-17 G. J. Schinner , J. Repp , E. Schubert , A. K. Rai , D. Reuter , A. D. Wieck , A. O. Govorov , A. W. Holleitner , J. P. Kotthaus

Thermoelectric devices at the nanoscale offer promising routes for on-chip refrigeration and waste-heat recovery, yet most semiconductor-based implementations suffer from limited tunability and narrow operational ranges. We introduce a…

Mesoscale and Nanoscale Physics · Physics 2025-08-29 Phillip Mercebach , Sun-Yong Hwang , Bo Lu , Björn Sothmann , Yukio Tanaka , Pablo Burset

We derive diffusion equations, which describe spin-charge coupled transport on the helical metal surface of a three-dimensional topological insulator. The main feature of these equations is a large magnitude of the spin-charge coupling,…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 A. A. Burkov , D. G. Hawthorn

All-electric devices for the generation and filtering of spin currents are of crucial importance for spintronics experiments and applications. Here we consider a quantum dot between two metallic leads in the presence of spin-orbit coupling,…

Mesoscale and Nanoscale Physics · Physics 2011-06-08 Valentina Brosco , Markus Jerger , Pablo San-Jose , Gergely Zarand , Alexander Shnirman , Gerd Schön

Weak topological insulators, constructed by stacking quantum spin Hall insulators with weak interlayer coupling, offer promising quantum electronic applications through topologically nontrivial edge channels. However, the currently…

We lay out an experiment to realize time-reversal invariant topological insulators in alkali atomic gases. We introduce an original method to synthesize a gauge field in the near-field of an atom-chip, which effectively mimics the effects…