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  1. Article: Ultrafast Dynamics of Valley-Polarized Excitons in WSe

    Koutenský, Petr / Slobodeniuk, Artur / Bartoš, Miroslav / Trojánek, František / Malý, Petr / Kozák, Martin

    Nanomaterials (Basel, Switzerland)

    2023  Volume 13, Issue 7

    Abstract: We report on the experimental investigation of the ultrafast dynamics of valley-polarized excitons in monolayer WSe2 using transient reflection spectroscopy with few-cycle laser pulses with 7 fs duration. We observe that at room temperature, the ... ...

    Abstract We report on the experimental investigation of the ultrafast dynamics of valley-polarized excitons in monolayer WSe2 using transient reflection spectroscopy with few-cycle laser pulses with 7 fs duration. We observe that at room temperature, the anisotropic valley population of excitons decays on two different timescales. The shorter decay time of approximately 120 fs is related to the initial hot exciton relaxation related to the fast direct recombination of excitons from the radiative zone, while the slower picosecond dynamics corresponds to valley depolarization induced by Coloumb exchange-driven transitions of excitons between two inequivalent valleys.
    Language English
    Publishing date 2023-03-28
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2662255-5
    ISSN 2079-4991
    ISSN 2079-4991
    DOI 10.3390/nano13071207
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Chiral Light Emission from a Hybrid Magnetic Molecule-Monolayer Transition Metal Dichalcogenide Heterostructure.

    Varade, Vaibhav / Haider, Golam / Slobodeniuk, Artur / Korytar, Richard / Novotny, Tomas / Holy, Vaclav / Miksatko, Jiri / Plsek, Jan / Sykora, Jan / Basova, Miriam / Zacek, Martin / Hof, Martin / Kalbac, Martin / Vejpravova, Jana

    ACS nano

    2023  Volume 17, Issue 3, Page(s) 2170–2181

    Abstract: Hybrid layered materials assembled from atomically thin crystals and small molecules bring great promises in pushing the current information and quantum technologies beyond the frontiers. We demonstrate here a class of layered valley-spin hybrid (VSH) ... ...

    Abstract Hybrid layered materials assembled from atomically thin crystals and small molecules bring great promises in pushing the current information and quantum technologies beyond the frontiers. We demonstrate here a class of layered valley-spin hybrid (VSH) materials composed of a monolayer two-dimensional (2D) semiconductor and double-decker single molecule magnets (SMMs). We have materialized a VSH prototype by thermal evaporation of terbium bis-phthalocyanine onto a MoS
    Language English
    Publishing date 2023-01-18
    Publishing country United States
    Document type Journal Article
    ISSN 1936-086X
    ISSN (online) 1936-086X
    DOI 10.1021/acsnano.2c08320
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Book ; Online: Nonequilibrium phase transition in transport through a driven quantum point contact

    Gamayun, Oleksandr / Slobodeniuk, Artur / Caux, Jean-Sébastien / Lychkovskiy, Oleg

    2020  

    Abstract: We study transport of noninteracting fermions through a periodically driven quantum point contact (QPC) connecting two tight-binding chains. Initially, each chain is prepared in its own equilibrium state, generally with a bias in chemical potentials and ... ...

    Abstract We study transport of noninteracting fermions through a periodically driven quantum point contact (QPC) connecting two tight-binding chains. Initially, each chain is prepared in its own equilibrium state, generally with a bias in chemical potentials and temperatures. We examine the heating rate (or, alternatively, energy increase per cycle) in the nonequilibrium time-periodic steady state established after initial transient dynamics. We find that the heating rate vanishes identically when the driving frequency exceeds the bandwidth of the chain. We first establish this fact for a particular type of QPC where the heating rate can be calculated analytically. Then we verify numerically that this nonequilibrium phase transition is present for a generic QPC. Finally, we derive this effect perturbatively in leading order for cases when the QPC Hamiltonian can be considered as a small perturbation. Strikingly, we discover that for certain QPCs the current averaged over the driving cycle also vanishes above the critical frequency, despite a persistent bias. This shows that a driven QPC can act as a frequency-controlled quantum switch.
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics ; Condensed Matter - Quantum Gases ; Quantum Physics
    Subject code 612
    Publishing date 2020-06-03
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: The optical response of monolayer, few-layer and bulk tungsten disulfide.

    Molas, Maciej R / Nogajewski, Karol / Slobodeniuk, Artur O / Binder, Johannes / Bartos, Miroslav / Potemski, Marek

    Nanoscale

    2017  Volume 9, Issue 35, Page(s) 13128–13141

    Abstract: We present a comprehensive optical study of thin flakes of tungsten disulfide ( ... ...

    Abstract We present a comprehensive optical study of thin flakes of tungsten disulfide (WS
    Language English
    Publishing date 2017-08-29
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515664-0
    ISSN 2040-3372 ; 2040-3364
    ISSN (online) 2040-3372
    ISSN 2040-3364
    DOI 10.1039/c7nr04672c
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book ; Online: Analogy and dissimilarity of excitons in monolayer and bilayer of MoSe$_2$

    Kipczak, Łucja / Slobodeniuk, Artur O. / Woźniak, Tomasz / Bhatnagar, Mukul / Zawadzka, Natalia / Olkowska-Pucko, Katarzyna / Grzeszczyk, Magdalena / Watanabe, Kenji / Taniguchi, Takashi / Babiński, Adam / Molas, Maciej R.

    2022  

    Abstract: Excitons in thin layers of semiconducting transition metal dichalcogenides are highly subject to the strongly modified Coulomb electron-hole interaction in these materials. Therefore, they do not follow the model system of a two-dimensional hydrogen atom. ...

    Abstract Excitons in thin layers of semiconducting transition metal dichalcogenides are highly subject to the strongly modified Coulomb electron-hole interaction in these materials. Therefore, they do not follow the model system of a two-dimensional hydrogen atom. We investigate experimentally and theoretically excitonic properties in both the monolayer (ML) and the bilayer (BL) of MoSe$_2$ encapsulated in hexagonal BN. The measured magnetic field evolutions of the reflectance contrast spectra of the MoSe$_2$ ML and BL allow us to determine $g$-factors of intralayer A and B excitons, as well as the $g$-factor of the interlayer exciton. We explain the dependence of $g$-factors on the number of layers and excitation state using first principles calculations. Furthermore, we demonstrate that the experimentally measured ladder of excitonic $s$ states in the ML can be reproduced using the $\mathbf{k\cdot p}$ approach with the Rytova-Keldysh potential that describes the electron-hole interaction. In contrast, the analogous calculation for the BL case requires taking into account the out-of-plane dielectric response of the MoSe$_2$ BL.

    Comment: 10 pages, 4 figures, + SM
    Keywords Condensed Matter - Mesoscale and Nanoscale Physics ; Condensed Matter - Materials Science
    Subject code 530
    Publishing date 2022-11-29
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Valley polarization of singlet and triplet trions in a WS

    Kapuściński, Piotr / Vaclavkova, Diana / Grzeszczyk, Magda / Slobodeniuk, Artur O / Nogajewski, Karol / Bartos, Miroslav / Watanabe, Kenji / Taniguchi, Takashi / Faugeras, Clément / Babiński, Adam / Potemski, Marek / Molas, Maciej R

    Physical chemistry chemical physics : PCCP

    2020  Volume 22, Issue 34, Page(s) 19155–19161

    Abstract: The spectral signatures associated with different negatively charged exciton complexes (trions) in a WS2 monolayer encapsulated in hBN are analyzed from low temperature and polarization resolved reflectance contrast (RC) and photoluminescence (PL) ... ...

    Abstract The spectral signatures associated with different negatively charged exciton complexes (trions) in a WS2 monolayer encapsulated in hBN are analyzed from low temperature and polarization resolved reflectance contrast (RC) and photoluminescence (PL) experiments, with an applied magnetic field. Based on results obtained from the RC experiment, we show that the valley Zeeman effect affects the optical response of both the singlet and the triplet trion species through the evolution of their energy and of their relative intensity, when applying an external magnetic field. Our analysis allows us to estimate a free electron concentration of ∼1.3 × 1011 cm-2. The observed evolutions based on PL experiments on the same sample are different and can hardly be understood within the same simple frame, highlighting the complexity of relaxation processes involved in the PL response.
    Language English
    Publishing date 2020-08-19
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d0cp02737e
    Database MEDical Literature Analysis and Retrieval System OnLINE

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