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We study spin dynamics of excitons confined in self-assembled CdSe quantum dots by means of optical orientation in magnetic field. At zero field the exciton emission from QDs populated via LO phonon-assisted absorption shows a circular…

Materials Science · Physics 2015-06-24 S. Mackowski , T. Gurung , H. E. Jackson , L. M. Smith , J. K. Furdyna , M. Dobrowolska

Increasing the speed limits of conventional electronics requires innovative approaches to manipulate other quantum properties of electrons besides their charge. An alternative approach utilizes the valley degree of freedom in…

Mesoscale and Nanoscale Physics · Physics 2023-03-29 A. O. Slobodeniuk , P. Koutenský , M. Bartoš , F. Trojánek , P. Malý , T. Novotný , M. Kozák

Exciton dispersion as a function of center-of-mass momentum, \textbf{Q}, is essential to the understanding of exciton dynamics. We use the ab-initio GW-Bethe Salpeter equation method to calculate the dispersion of excitons in monolayer…

Materials Science · Physics 2015-12-23 Diana. Y. Qiu , Ting Cao , Steven G. Louie

We report on the kinetics of a low-temperature gas of indirect excitons in the optically-induced exciton trap. The excitons in the region of laser excitation are found to rapidly -- within 4 ns -- cool to the lattice temperature T = 1.4 K,…

Mesoscale and Nanoscale Physics · Physics 2010-03-22 A. T. Hammack , L. V. Butov , L. Mouchliadis , A. L. Ivanov , A. C. Gossard

We study photoluminescence (PL) spectra and exciton dynamics of MoS$_2$ monolayer (ML) grown by the chemical vapor deposition technique. In addition to the usual direct A-exciton line we observe a low-energy line of bound excitons…

Mesoscale and Nanoscale Physics · Physics 2021-09-14 M. A. Akmaev , M. M. Glazov , M. V. Kochiev , P. V. Vinokurov , S. A. Smagulova , V. V. Belykh

The direct gap interband transitions in transition metal dichalcogenides monolayers are governed by chiral optical selection rules. Determined by laser helicity, optical transitions in either the $K^+$ or $K^-$ valley in momentum space are…

Mesoscale and Nanoscale Physics · Physics 2016-10-26 G. Wang , X. Marie , B. L. Liu , T. Amand , C. Robert , F. Cadiz , P. Renucci , B. Urbaszek

We report on the influence of a photochemical doping method on the spin-valley polarization degree ($P_{c}$) of excitons in WSe$_2$ monolayers. By varying the carrier density and transitioning from an excess of electrons (n-type) to an…

We use molecular dynamics computer simulations to investigate the coupling/decoupling between translational and rotational dynamics in a glass-forming liquid of dumbbells. This is done via a careful analysis of the $\alpha$-relaxation time…

Soft Condensed Matter · Physics 2009-11-13 Song-Ho Chong , Walter Kob

Moir\'{e} excitons (MXs) are electron-hole pairs localised by the periodic (moir\'{e}) potential forming in two-dimensional heterostructures (HSs). MXs can be exploited, $e.g.$, for creating nanoscale-ordered quantum emitters and achieving…

Cyclotron resonance of two-dimensional electrons is studied at low temperatures down to 0.4 K for a high-mobility Si/SiGe quantum well which exhibits a metallic temperature dependence of dc resistivity $\rho$. The relaxation time $\tau_{\rm…

Mesoscale and Nanoscale Physics · Physics 2015-05-28 Ryuichi Masutomi , Kohei Sasaki , Ippei Yasuda , Akihito Sekine , Kentarou Sawano , Yasuhiro Shiraki , Tohru Okamoto

The interactions between charges and excitons involve complex many-body interactions at high densities. The exciton-polaron model has been adopted to understand the Fermi sea screening of charged excitons in monolayer transition metal…

Mesoscale and Nanoscale Physics · Physics 2023-09-14 Xin Cong , Parisa Ali Mohammadi , Mingyang Zheng , Kenji Watanabe , Takashi Taniguchi , Daniel Rhodes , Xiao-Xiao Zhang

Monolayer (1L) transition metal dichalcogenides (TMDs) provide a unique opportunity to control the valley degree of freedom of optically excited charge carriers due to the spin-valley locking effect. Despite extensive studies of the…

In monolayer MoS2 optical transitions across the direct bandgap are governed by chiral selection rules, allowing optical valley initialization. In time resolved photoluminescence (PL) experiments we find that both the polarization and…

Mesoscale and Nanoscale Physics · Physics 2014-02-04 D. Lagarde , L. Bouet , X. Marie , C. R. Zhu , B. L. Liu , T. Amand , P. H. Tan , B. Urbaszek

We demonstrate a new method of measuring the exciton spin relaxation time in semiconductor nanostructures by continuous-wave photoluminescence. We find that for self-assembled CdTe quantum dots the degree of circular polarization of…

Materials Science · Physics 2009-11-10 S. Mackowski , T. A. Nguyen , H. E. Jackson , L. M. Smith , J. Kossut , G. Karczewski

We consider the problem of relaxation in a one-dimensional system of interacting electrons. In the limit of weak interactions, we calculate the decay rate of a single-electron excitation, accounting for the nonlinear dispersion. The leading…

Strongly Correlated Electrons · Physics 2013-04-09 Zoran Ristivojevic , K. A. Matveev

For monolayer transition metal chalcogenides (TMDs), electrons and excitons in different valleys can be driven to opposite directions by the Berry curvature, serving as a valley-dependent effective magnetic field. In addition to monolayer…

Mesoscale and Nanoscale Physics · Physics 2019-04-23 Zumeng Huang , Yuanda Liu , Kévin Dini , Zhuojun Liu , Hanlin Fang , Jin Liu , Timothy Liew , Weibo Gao

Recent experiments on liquid water show collective dipole orientation fluctuations dramatically slower then expected (with relaxation time $>$ 50 ns) [D. P. Shelton, Phys. Rev. B {\bf 72}, 020201(R) (2005)]. Molecular dynamics simulations…

Soft Condensed Matter · Physics 2009-11-11 Pradeep Kumar , Giancarlo Franzese , Sergey V. Buldyrev , H. Eugene Stanley

Atomically thin crystals of transition metal dichalcogenides are ideally suited to study the interplay of light-matter coupling, polarization and magnetic field effects. In this work, we investiagte the formation of exciton-polaritons in a…

A single monolayer of the layered semimetal WTe2 behaves as a two-dimensional topological insulator, with helical conducting edge modes surrounding a bulk state that becomes insulating at low temperatures. Here we present evidence that the…

A direct band gap, remarkable light-matter coupling as well as strong spin-orbit and Coulomb interaction establish two-dimensional (2D) crystals of transition metal dichalcogenides (TMDs) as an emerging material class for fundamental…

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