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We use a combination of molecular dynamics and quantum transport simulations to investigate the upper limit of spin transport in suspended graphene. We find that thermally-induced atomic-scale corrugations are the dominant factor, limiting…

Mesoscale and Nanoscale Physics · Physics 2024-12-30 Aron W. Cummings , Simon M. -M. Dubois , Pedro Alcázar Guerrero , Jean-Christophe Charlier , Stephan Roche

The generation of an out-of-equilibrium population of spin-polarized carriers is a keystone process for quantum technologies and spintronics alike. It can be achieved through the so-called optical spin orientation by exciting the material…

Spin orientation of photoexcited carriers and their energy relaxation is investigated in bulk Ge by studying spin-polarized recombination across the direct band gap. The control over parameters such as doping and lattice temperature is…

Materials Science · Physics 2013-07-24 F. Pezzoli , L. Qing , A. Giorgioni , G. Isella , E. Grilli , M. Guzzi , H. Dery

The twist degree of freedom provides a powerful new tool for engineering the electrical and optical properties of van der Waals heterostructures. Here, we show that the twist angle can be used to control the spin-valley properties of…

Spin blockade occurs when an electron is unable to access an energetically favorable path through a quantum dot due to spin conservation, resulting in a blockade of the current through the dot. Spin blockade is the basis of a number of…

Spins of charge carriers, paramagnetic centers, and nuclei in semiconductor structures are known to be oriented if circular-polarized light is shined upon the structure. This is due to transfer of angular momentum from photons to various…

Condensed Matter · Physics 2007-05-23 Kirill Kavokin

Spin defects in silicon carbide have exceptional electron spin coherence with a near-infrared spin-photon interface in a material amenable to modern semiconductor fabrication. Leveraging these advantages, we successfully integrate highly…

We investigated the spin coherence of high-mobility two-dimensional electron gases confined in multilayer GaAs quantum wells. The dynamics of the spin polarization was optically studied using pump-probe techniques: time-resolved Kerr…

Mesoscale and Nanoscale Physics · Physics 2016-06-02 S. Ullah , G. M. Gusev , A. K. Bakarov , F. G. G. Hernandez

Spintronics in halide perovskites has drawn significant attention in recent years, due to highly tunable spin-orbit fields and intriguing interplay with lattice symmetry. Spin lifetime -- a key parameter that determines the applicability of…

Materials Science · Physics 2023-10-25 Junqing Xu , Kejun Li , Uyen N. Huynh , Jinsong Huang , Ravishankar Sundararaman , Valy Vardeny , Yuan Ping

Using circularly polarized light is an alternative to electronic ways for spin injection into materials. Spins are injected at a point of the light illumination, and then diffuse and spread radially due to the in-plane gradient of the spin…

Mesoscale and Nanoscale Physics · Physics 2020-04-29 Di Fan , Rei Hobara , Ryota Akiyama , Shuji Hasegawa

We report the observation of the quantum-confined Stark effect in Ge/SiGe multiple quantum well heterostructures grown on Si(0.22)Ge(0.78) virtual substrates. The large compressive strain in the Ge quantum well layers caused by the lattice…

Mesoscale and Nanoscale Physics · Physics 2013-03-01 L. Lever , Z. Ikonić , A. Valavanis , R. W. Kelsall , M. Myronov , D. R. Leadley , Y. Hu , N. Owens , F. Y. Gardes , G. T. Reed

We demonstrate methods to locally control the spin rotation of moving electrons in a GaAs channel. The Larmor frequency of optically-injected spins is modulated when the spins are dragged through a region of spin-polarized nuclei created at…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 M. E. Nowakowski , G. D. Fuchs , S. Mack , N. Samarth , D. D. Awschalom

In semiconductors, photoexcited electrons and holes (carriers) initially occupy high-energy states, but quickly lose energy to phonons and relax to the band edge within a picosecond [1]. Increasing the lifetime of carriers in…

Materials Science · Physics 2015-04-15 Jonathan Trinastic , Iek-Heng Chu , Hai-Ping Cheng

Pulsed electron paramagnetic resonance spectroscopy of the photoexcited, metastable triplet state of the oxygen-vacancy center in silicon reveals that the lifetime of the ms = \pm1 sub-levels differ significantly from that of the ms =0…

Transition metal dichalcogenides (TMDs) combine interesting optical and spintronic properties in an atomically-thin material, where the light polarization can be used to control the spin and valley degrees-of-freedom for the development of…

Mesoscale and Nanoscale Physics · Physics 2021-03-10 Carmem M. Gilardoni , Freddie Hendriks , Caspar H. van der Wal , Marcos H. D. Guimarães

The population dynamics of dark and bright excitons in (In,Ga)As/GaAs quantum dots is studied by two-color pump-probe spectroscopy in an external magnetic field. With the field applied in Faraday geometry and at T<20 K, the dark excitons…

Mesoscale and Nanoscale Physics · Physics 2012-05-08 H. Kurtze , D. R. Yakovlev , D. Reuter , A. D. Wieck , M. Bayer

In this work, we investigate hole spin-flip transitions in a single self-assembled InGaAs/GaAs quantum dot. We find the hole wave functions using the 8-band $kp$ model and calculate phonon-assisted spin relaxation rates for the ground-state…

Mesoscale and Nanoscale Physics · Physics 2020-11-11 Mateusz Krzykowski , Krzysztof Gawarecki , Pawel Machnikowski

Spin sensitive bleaching of the absorption of far-infrared radiation has been observed in $p$-type GaAs/AlGaAs quantum well structures. The absorption of circularly polarized radiation saturates at lower intensities than that of linearly…

The spin-Hall conductivity in spatially-homogeneous two-dimensional electron systems described by the spin-orbit Hamiltonian \hbar \Omega_p \sigma is presented as a sum of the universal part Me/8 \pi \hbar determined by the Berry phase…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 O. E. Raichev

We present a microscopic theory of spin-orbit coupling in the integer quantum Hall regime. The spin-orbit scattering length is evaluated in the limit of long-range random potential. The spin-flip rate is shown to be determined by rare…

Condensed Matter · Physics 2009-10-28 D. G. Polyakov
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