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Controlling the flow of electrons by manipulation of their spin is a key to the development of spin-based electronics. While recent demonstrations of electrical-gate control in spin-transistor configurations show great promise, operation at…

Mesoscale and Nanoscale Physics · Physics 2012-12-14 Luyi Yang , J. D. Koralek , J. Orenstein , D. R. Tibbetts , J. L. Reno , M. P. Lilly

We fabricated Quantum Dot (QD) devices using a standard SOI CMOS process flow, and demonstrated that the spin of confined electrons could be controlled via a local electrical-field excitation, owing to inter-valley spin-orbit coupling. We…

We study the thermoelectric response of a device containing a pair of helical edge states contacted at the same temperature $T$ and chemical potential $\mu$ and connected to an external reservoir, with different chemical potential and…

Strongly Correlated Electrons · Physics 2018-11-28 P. Roura-Bas , Liliana. Arrachea , Eduardo Fradkin

The spin dynamics in a broad range of systems can be studied using circularly polarized optical excitation with alternating helicity. The dependence of spin polarization on the frequency of helicity alternation, known as the spin inertia…

Mesoscale and Nanoscale Physics · Physics 2018-09-19 E. A. Zhukov , E. Kirstein , D. S. Smirnov , D. R. Yakovlev , M. M. Glazov , D. Reuter , A. D. Wieck , M. Bayer , A. Greilich

We show that by illuminating an InGaAs/GaAs self-assembled quantum dot with circularly polarized light, the nuclei of atoms constituting the dot can be driven into a bistable regime, in which either a threshold-like enhancement or reduction…

We investigated optical spin orientation and dynamic nuclear polarization (DNP) in individual self-assembled InGaAs/GaAs quantum dots (QDs) doped by a single Mn atom, a magnetic impurity providing a neutral acceptor A$^0$ with an effective…

Mesoscale and Nanoscale Physics · Physics 2016-11-15 O. Krebs , E. Baudin , A. Lemaître

Spin-orbit coupling in semiconductors relates the spin of an electron to its momentum and provides a pathway for electrically initializing and manipulating electron spins for applications in spintronics and spin-based quantum information…

Mesoscale and Nanoscale Physics · Physics 2015-06-25 V. Sih , R. C. Myers , Y. K. Kato , W. H. Lau , A. C. Gossard , D. D. Awschalom

We employ optical pump-probe spectroscopy to investigate the voltage dependence of spontaneous electron and nuclear spin polarizations in hybrid MnAs/n-GaAs and Fe/n-GaAs Schottky diodes. Through the hyperfine interaction, nuclear spin…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 R. J. Epstein , J. Stephens , M. Hanson , Y. Chye , A. C. Gossard , P. M. Petroff , D. D. Awschalom

We study theoretically the cooling of an ensemble of nuclear spins coupled to the spin of a localized electron in a quantum dot. We obtain a master equation for the state of the nuclear spins interacting with a sequence of polarized…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 H. Christ , J. I. Cirac , G. Giedke

We suggest a new spin orientation mechanism for localized electrons: $dynamic~electron~spin~polarization~provided~by~nuclear~spin~fluctuations$. The angular momentum for the electrons is gained from the nuclear spin system via the hyperfine…

Mesoscale and Nanoscale Physics · Physics 2020-10-14 D. S. Smirnov , T. S. Shamirzaev , D. R. Yakovlev , M. Bayer

We report electrical spin injection from a ferromagnetic metal contact into a semiconductor light emitting diode structure with an injection efficiency of 30% which persists to room temperature. The Schottky barrier formed at the Fe/AlGaAs…

Materials Science · Physics 2009-11-07 Aubrey T. Hanbicki , B. T. Jonker , G. Itskos , G. Kioseoglou , A. Petrou

We report the observation of an anomalous conductance plateau near G = 0.5 G0 (G0 = 2e2/h) in asymmetrically biased AlGaAs/GaAs quantum point contacts (QPCs), with in-plane side gates in the presence of lateral spin-orbit coupling. This is…

Mesoscale and Nanoscale Physics · Physics 2012-04-24 N. Bhandari , P. P. Das , M. Cahay , R. S. Newrock , S. T. Herbert

Sharp threshold-like transitions between two stable nuclear spin polarizations are observed in optically pumped individual InGaAs self-assembled quantum dots embedded in a Schottky diode when the bias applied to the diode is tuned. The…

While microscopic laws of physics are invariant under the reversal of the arrow of time, the transport of energy and information in most devices is an irreversible process. It is this irreversibility that leads to intrinsic dissipations in…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Shuichi Murakami , Naoto Nagaosa , Shou-Cheng Zhang

It is shown that, for appropriate values of electron energy, the silicene dot can work as a controllable spin polarizer. The spin polarizer can polarize the spin of transmitted electrons from nearly pure down to nearly pure up by changing…

Mesoscale and Nanoscale Physics · Physics 2015-01-19 Hamidreza Simchi , Mahdi Esmaeilzadeh , Hossein Mazidabadi , Mohammad Norouzi

Spontaneous nuclear polarization is predicted in double quantum dots in the spin-blocked electron transport regime. The polarization results from an instability of the zero-polarization state when singlet and triplet electron energy levels…

Mesoscale and Nanoscale Physics · Physics 2010-08-23 M. S. Rudner , L. S. Levitov

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 have studied the physical processes responsible for the spin -flip in GaAs quantum dots. We have calculated the rates for different mechanisms which are related to spin-orbit coupling and cause a spin-flip during the inelastic relaxation…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander V. Khaetskii , Yuli V. Nazarov

We study a system in which electrons in a two-dimensional electron gas are confined by a nonhomogeneous nuclear spin polarization. The system consists of a heterostructure that has non-zero nuclei spins. We show that in this system…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yu. V. Pershin

The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin-lattice (T1) and spin-spin (T2) relaxation times of electrons. Minimising the effects of spin-orbit…

Materials Science · Physics 2016-11-24 Bálint Náfrádi , Mohammad Choucair , Klaus-Peter Dinse , László Forró