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Smoleński T, Kazimierczuk T, Goryca M, Nogajewski K, Potemski M, Kossacki P. Valley pseudospin relaxation of charged excitons in monolayer MoTe 2. J Phys Condens Matter 2021; 33:025701. [PMID: 33055370 DOI: 10.1088/1361-648x/abb1cb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Zeeman effect induced by the magnetic field introduces a splitting between the two valleys at K + and K - points of the Brillouin zone in monolayer semiconducting transition metal dichalcogenides. In consequence, the photoluminescence signal exhibits a field dependent degree of circular polarization. We present a comprehensive study of this effect in the case of a trion in monolayer MoTe2, showing that although time integrated data allows us to deduce a g-factor of the trion state, such an analysis cannot be substantiated by the timescales revealed in the time-resolved experiments.
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Affiliation(s)
- T Smoleński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
- Institute for Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - T Kazimierczuk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - M Goryca
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - K Nogajewski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - M Potemski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
- Laboratoire National des Champs Magnetiques Intenses, CNRS-UGA-UPS-INSA-EMFL, 25 rue des Martyrs, 38042 Grenoble, France
| | - P Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
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2
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Li J, Goryca M, Wilson NP, Stier AV, Xu X, Crooker SA. Spontaneous Valley Polarization of Interacting Carriers in a Monolayer Semiconductor. Phys Rev Lett 2020; 125:147602. [PMID: 33064502 DOI: 10.1103/physrevlett.125.147602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
We report magnetoabsorption spectroscopy of gated WSe_{2} monolayers in high magnetic fields up to 60 T. When doped with a 2D Fermi sea of mobile holes, well-resolved sequences of optical transitions are observed in both σ^{±} circular polarizations, which unambiguously and separately indicate the number of filled Landau levels (LLs) in both K and K^{'} valleys. This reveals the interaction-enhanced valley Zeeman energy, which is found to be highly tunable with hole density p. We exploit this tunability to align the LLs in K and K^{'}, and find that the 2D hole gas becomes unstable against small changes in LL filling and can spontaneously valley polarize. These results cannot be understood within a single-particle picture, highlighting the importance of exchange interactions in determining the ground state of 2D carriers in monolayer semiconductors.
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Affiliation(s)
- J Li
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M Goryca
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - N P Wilson
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - A V Stier
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - X Xu
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - S A Crooker
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Łopion A, Goryca M, Smoleński T, Oreszczuk K, Nogajewski K, Molas MR, Potemski M, Kossacki P. Temperature dependence of photoluminescence lifetime of atomically-thin WSe 2 layer. Nanotechnology 2020; 31:135002. [PMID: 31825902 DOI: 10.1088/1361-6528/ab60ca] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
At cryogenic temperatures, the photoluminescence (PL) spectrum of monolayer WSe2 features a number of lines related to the recombination of so-called localized excitons (LEs). The intensity of these lines strongly decreases with increasing temperature. In order to understand the mechanism behind this phenomenon we carried out a time-resolved experiment, which revealed a similar trend in the PL decay time. Our results identify the opening of additional non-radiative relaxation channels as a primary cause of the observed temperature quenching of the LEs' PL.
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Affiliation(s)
- A Łopion
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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Goryca M, Wilson NP, Dey P, Xu X, Crooker SA. Detection of thermodynamic "valley noise" in monolayer semiconductors: Access to intrinsic valley relaxation time scales. Sci Adv 2019; 5:eaau4899. [PMID: 30838326 PMCID: PMC6397030 DOI: 10.1126/sciadv.aau4899] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 01/14/2019] [Indexed: 06/09/2023]
Abstract
Together with charge and spin, many novel two-dimensional materials also permit information to be encoded in an electron's valley degree of freedom-that is, in particular momentum states in the material's Brillouin zone. With a view toward valley-based (opto)electronic technologies, the intrinsic time scales of valley scattering are therefore of fundamental interest. Here, we demonstrate an entirely noise-based approach for exploring valley dynamics in monolayer transition-metal dichalcogenide semiconductors. Exploiting their valley-specific optical selection rules, we use optical Faraday rotation to passively detect the thermodynamic fluctuations of valley polarization in a Fermi sea of resident carriers. This spontaneous "valley noise" reveals narrow Lorentzian line shapes and, therefore, long exponentially-decaying intrinsic valley relaxation. Moreover, the noise signatures validate both the relaxation times and the spectral dependence of conventional (perturbative) pump-probe measurements. These results provide a viable route toward quantitative measurements of intrinsic valley dynamics, free from any external perturbation, pumping, or excitation.
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Affiliation(s)
- M. Goryca
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - N. P. Wilson
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - P. Dey
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
| | - X. Xu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - S. A. Crooker
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
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Kobak J, Smoleński T, Goryca M, Rousset JG, Pacuski W, Bogucki A, Oreszczuk K, Kossacki P, Nawrocki M, Golnik A, Płachta J, Wojnar P, Kruse C, Hommel D, Potemski M, Kazimierczuk T. Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots. J Phys Condens Matter 2016; 28:265302. [PMID: 27173643 DOI: 10.1088/0953-8984/28/26/265302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a comparative study of two self-assembled quantum dot (QD) systems based on II-VI compounds: CdTe/ZnTe and CdSe/ZnSe. Using magneto-optical techniques we investigated a large population of individual QDs. The systematic photoluminescence studies of emission lines related to the recombination of neutral exciton X, biexciton XX, and singly charged excitons (X(+), X(-)) allowed us to determine average parameters describing CdTe QDs (CdSe QDs): X-XX transition energy difference 12 meV (24 meV); fine-structure splitting δ1=0.14 meV (δ1=0.47 meV); g-factor g = 2.12 (g = 1.71); diamagnetic shift γ=2.5 μeV T(-2) (γ =1.3 μeV T(-2)). We find also statistically significant correlations between various parameters describing internal structure of excitonic complexes.
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Affiliation(s)
- J Kobak
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
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Smoleński T, Kazimierczuk T, Kobak J, Goryca M, Golnik A, Kossacki P, Pacuski W. Magnetic ground state of an individual Fe(2+) ion in strained semiconductor nanostructure. Nat Commun 2016; 7:10484. [PMID: 26818580 PMCID: PMC4738340 DOI: 10.1038/ncomms10484] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 12/17/2015] [Indexed: 11/15/2022] Open
Abstract
Single impurities with nonzero spin and multiple ground states offer a degree of freedom that can be utilized to store the quantum information. However, Fe(2+) dopant is known for having a single nondegenerate ground state in the bulk host semiconductors and thus is of little use for spintronic applications. Here we show that the well-established picture of Fe(2+) spin configuration can be modified by subjecting the Fe(2+) ion to high strain, for example, produced by lattice mismatched epitaxial nanostructures. Our analysis reveals that high strain induces qualitative change in the ion energy spectrum and results in nearly doubly degenerate ground state with spin projection Sz= ± 2. We provide an experimental proof of this concept using a new system: a strained epitaxial quantum dot containing individual Fe(2+) ion. Magnetic character of the Fe(2+) ground state in a CdSe/ZnSe dot is revealed in photoluminescence experiments by exploiting a coupling between a confined exciton and the single-iron impurity. We also demonstrate that the Fe(2+) spin can be oriented by spin-polarized excitons, which opens a possibility of using it as an optically controllable two-level system free of nuclear spin fluctuations.
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Affiliation(s)
- T. Smoleński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - T. Kazimierczuk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - J. Kobak
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - M. Goryca
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - A. Golnik
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - P. Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - W. Pacuski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
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7
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Kobak J, Smoleński T, Goryca M, Papaj M, Gietka K, Bogucki A, Koperski M, Rousset JG, Suffczyński J, Janik E, Nawrocki M, Golnik A, Kossacki P, Pacuski W. Designing quantum dots for solotronics. Nat Commun 2015; 5:3191. [PMID: 24463946 PMCID: PMC3916836 DOI: 10.1038/ncomms4191] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 01/02/2014] [Indexed: 01/28/2023] Open
Abstract
Solotronics, optoelectronics based on solitary dopants, is an emerging field of research and technology reaching the ultimate limit of miniaturization. It aims at exploiting quantum properties of individual ions or defects embedded in a semiconductor matrix. It has already been shown that optical control of a magnetic ion spin is feasible using the carriers confined in a quantum dot. However, a serious obstacle was the quenching of the exciton luminescence by magnetic impurities. Here we show, by photoluminescence studies on thus-far-unexplored individual CdTe dots with a single cobalt ion and CdSe dots with a single manganese ion, that even if energetically allowed, nonradiative exciton recombination through single-magnetic-ion intra-ionic transitions is negligible in such zero-dimensional structures. This opens solotronics for a wide range of as yet unconsidered systems. On the basis of results of our single-spin relaxation experiments and on the material trends, we identify optimal magnetic-ion quantum dot systems for implementation of a single-ion-based spin memory. Single-atom dopants embedded in a semiconductor matrix are of potential use for optical, spintronics as well as information storage applications. Here, Kobak et al. realize CdTe and CdSe quantum dots with single cobalt and manganese ions and show how the quantum dot design influences single-spin relaxation time.
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Affiliation(s)
- J Kobak
- 1] Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland [2]
| | - T Smoleński
- 1] Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland [2]
| | - M Goryca
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - M Papaj
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - K Gietka
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - A Bogucki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - M Koperski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - J-G Rousset
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - J Suffczyński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - E Janik
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - M Nawrocki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - A Golnik
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - P Kossacki
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
| | - W Pacuski
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Hoża 69, Warsaw 00-681, Poland
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Goryca M, Koperski M, Wojnar P, Smoleński T, Kazimierczuk T, Golnik A, Kossacki P. Coherent Precession of an Individual 5/2 Spin. Phys Rev Lett 2014; 113:227202. [PMID: 25494084 DOI: 10.1103/physrevlett.113.227202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Indexed: 06/04/2023]
Abstract
We present direct observation of a coherent spin precession of an individual Mn^{2+} ion, having both electronic and nuclear spins equal to 5/2, embedded in a CdTe quantum dot and placed in a magnetic field. The spin state evolution is probed in a time-resolved pump-probe measurement of absorption of the single dot. The experiment reveals subtle details of the large-spin coherent dynamics, such as nonsinusoidal evolution of states occupation, and beatings caused by the strain-induced differences in energy levels separation. Sensitivity of the large-spin impurity on the crystal strain opens the possibility of using it as a local strain probe.
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Affiliation(s)
- M Goryca
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
| | - M Koperski
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
| | - P Wojnar
- Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-688 Warszawa, Poland
| | - T Smoleński
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
| | - T Kazimierczuk
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
| | - A Golnik
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
| | - P Kossacki
- Institute of Experimental Physics, University of Warsaw, ul. Hoża 69, 00-681 Warszawa, Poland
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9
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Trojnar AH, Korkusiński M, Kadantsev ES, Hawrylak P, Goryca M, Kazimierczuk T, Kossacki P, Wojnar P, Potemski M. Quantum interference in exciton-Mn spin interactions in a CdTe semiconductor quantum dot. Phys Rev Lett 2011; 107:207403. [PMID: 22181774 DOI: 10.1103/physrevlett.107.207403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Indexed: 05/31/2023]
Abstract
We show theoretically and experimentally the existence of a new quantum-interference effect between the electron-hole interactions and the scattering by a single Mn impurity. The theoretical model, including electron-valence-hole correlations, the short- and long-range exchange interaction of a Mn ion with the heavy hole and with electron and anisotropy of the quantum dot, is compared with photoluminescence spectroscopy of CdTe dots with single magnetic ions. We show how the design of the electronic levels of a quantum dot enables the design of an exciton, control of the quantum interference, and hence engineering of light-Mn interaction.
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Affiliation(s)
- A H Trojnar
- Institute for Microstructural Sciences, National Research Council, Ottawa, Canada
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Goryca M, Kazimierczuk T, Nawrocki M, Golnik A, Gaj JA, Kossacki P, Wojnar P, Karczewski G. Optical manipulation of a single Mn spin in a CdTe-based quantum dot. Phys Rev Lett 2009; 103:087401. [PMID: 19792759 DOI: 10.1103/physrevlett.103.087401] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Indexed: 05/28/2023]
Abstract
Two coupled CdTe quantum dots, selected from a self-assembled system, one of them containing a single Mn ion, were studied by continuous wave and modulated photoluminescence, photoluminescence excitation, and photon correlation experiments. Optical writing of information on the spin state of the Mn ion has been demonstrated, using the orientation of the Mn spin by spin-polarized carriers transferred from the neighboring quantum dot. Mn spin orientation time values from 20 to 100 ns were measured, depending on the excitation power. Storage time of the information on the Mn spin was found to be enhanced by application of a static magnetic field of 1 T, reaching hundreds of microseconds in the dark. Simple rate equation models were found to describe correctly the static and dynamical properties of the system.
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Affiliation(s)
- M Goryca
- Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw, Poland.
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11
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Goryca M, Ferrand D, Kossacki P, Nawrocki M, Pacuski W, Maślana W, Gaj JA, Tatarenko S, Cibert J, Wojtowicz T, Karczewski G. Magnetization dynamics down to a zero field in dilute (Cd,Mn)Te quantum wells. Phys Rev Lett 2009; 102:046408. [PMID: 19257452 DOI: 10.1103/physrevlett.102.046408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Indexed: 05/27/2023]
Abstract
The evolution of the magnetization in (Cd,Mn)Te quantum wells after a short pulse of magnetic field was determined from the giant Zeeman shift of spectroscopic lines. The dynamics in the absence of a static magnetic field was found to be up to 3 orders of magnitude faster than that at 1 T. Hyperfine interaction and strain are mainly responsible for the fast decay. The influence of a hole gas is clearly visible: at zero field anisotropic holes stabilize the system of Mn ions, while in a magnetic field of 1 T they are known to speed up the decay by opening an additional relaxation channel.
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Affiliation(s)
- M Goryca
- Institute of Experimental Physics, University of Warsaw, Hoza 69, PL-00-681 Warszawa, Poland.
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