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Howarth J, Vaklinova K, Grzeszczyk M, Baldi G, Hague L, Potemski M, Novoselov KS, Kozikov A, Koperski M. Electroluminescent vertical tunneling junctions based on WSe 2 monolayer quantum emitter arrays: Exploring tunability with electric and magnetic fields. Proc Natl Acad Sci U S A 2024; 121:e2401757121. [PMID: 38820004 PMCID: PMC11161753 DOI: 10.1073/pnas.2401757121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/29/2024] [Indexed: 06/02/2024] Open
Abstract
We experimentally demonstrate the creation of defects in monolayer WSe2 via nanopillar imprinting and helium ion irradiation. Based on the first method, we realize atomically thin vertical tunneling light-emitting diodes based on WSe2 monolayers hosting quantum emitters at deterministically specified locations. We characterize these emitters by investigating the evolution of their emission spectra in external electric and magnetic fields, as well as by inducing electroluminescence at low temperatures. We identify qualitatively different types of quantum emitters and classify them according to the dominant electron-hole recombination paths, determined by the mechanisms of intervalley mixing occurring in fundamental conduction and/or valence subbands.
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Affiliation(s)
- James Howarth
- School of Physics and Astronomy, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Kristina Vaklinova
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore117544, Singapore
| | - Magdalena Grzeszczyk
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore117544, Singapore
| | - Giulio Baldi
- Department of Physics, National University of Singapore, Singapore119077, Singapore
| | - Lee Hague
- School of Physics and Astronomy, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Marek Potemski
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-Université Paul Sabatier-Institut National des Sciences Appliquées Toulouse, Grenoble38042, France
- Center for Terahertz Research and Applications Labs, Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw01-142, Poland
| | - Kostya S. Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore117575, Singapore
| | - Aleksey Kozikov
- Faculty of Science, Agriculture & Engineering, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle Upon TyneNE1 7RU, United Kingdom
| | - Maciej Koperski
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore117544, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore117575, Singapore
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2
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Nishimura H, Enomoto K, Pu YJ, Kim D. Hydrothermal synthesis of water-soluble Mn- and Cu-doped CdSe quantum dots with multi-shell structures and their photoluminescence properties. RSC Adv 2022; 12:6255-6264. [PMID: 35424533 PMCID: PMC8982036 DOI: 10.1039/d1ra08491g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/16/2022] [Indexed: 12/03/2022] Open
Abstract
Optical properties of semiconductor quantum dots (QDs) can be tuned by doping with transition metal ions. In this study, water-soluble CdSe/ZnS:Mn/ZnS QDs with the core/shell/shell structure were synthesized through a hydrothermal method, in which the surface of the CdSe core was coated with a ZnS:Mn shell and ZnS capping shell. Herein, the CdSe core QDs were prepared first and then doped with Mn2+; therefore, the QD size and doping level could be controlled independently and interference from the self-purifying effect could be avoided. When CdSe cores with diameters less than 1.9 nm were used, Mn-related photoluminescence (PL) was observed as the main PL band, whereas the band-edge PL was mainly observed when larger CdSe cores were used. Furthermore, using ZnS:Cu as the doping shell layer, CdSe/ZnS:Cu/ZnS and ZnSe/ZnS:Cu/ZnS nanoparticles were successfully synthesized, and Cu-related PL was clearly observed. These results indicate that the core/shell/shell QD structure with doping in the shell layer is a versatile method for synthesizing doped QDs.
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Affiliation(s)
- Hisaaki Nishimura
- Department of Applied Physics, Osaka City University Osaka 558-8585 Japan
| | - Kazushi Enomoto
- RIKEN Center for Emergent Matter Science (CEMS) Saitama 351-0198 Japan
| | - Yong-Jin Pu
- RIKEN Center for Emergent Matter Science (CEMS) Saitama 351-0198 Japan
| | - DaeGwi Kim
- Department of Applied Physics, Osaka City University Osaka 558-8585 Japan
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3
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Abdelmonem AM, Zámbó D, Rusch P, Schlosser A, Klepzig LF, Bigall NC. Versatile Route for Multifunctional Aerogels Including Flaxseed Mucilage and Nanocrystals. Macromol Rapid Commun 2022; 43:e2100794. [PMID: 35085414 DOI: 10.1002/marc.202100794] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/14/2022] [Indexed: 11/05/2022]
Abstract
Preparation of low density monolithic and free-standing organic-inorganic hybrid aerogels of various properties is demonstrated using green chemistry from a biosafe natural source (flaxseed mucilage) and freeze-casting and subsequent freeze drying. Bio-aerogels, luminescent aerogels and magneto-responsive aerogels were obtained by combination of the flaxseed mucilage with different types of nanoparticles. Moreover, the aerogels are investigated as possible drug release system using curcumin as a model. Various characterization techniques like thermogravimetric analysis, nitrogen physisorption, electron microscopy, UV/Vis absorption and emission spectroscopy, bulk density and mechanical measurements as well as in vitro release profile measurements are employed to investigate the obtained materials. The flaxseed-inspired organic-inorganic hybrid aerogels exhibit ultra-low densities of as low as 5.6 mg/cm3 for 0.5% (w/v) mucilage polymer, a specific surface area of 4 to 20 m2 /g, high oil absorption capacity (23 g/g) and prominent compressibility. The natural biopolymer technique leads to low cost and biocompatible functional lightweight materials with tunable properties (physicochemical and mechanical) and significant potential for applications as supporting or stimuli responsive materials, carriers, reactors, microwave, and electromagnetic radiation protective (absorbing) material as well as in drug delivery and oil absorption. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Abuelmagd M Abdelmonem
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany.,Food Technology Research Institute, Agricultural Research Center, 9 Cairo University St., Giza, 12619, Egypt
| | - Dániel Zámbó
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany.,Institute of Technical Physics and Materials Science, Centre for Energy Research, Konkoly-Thege M. str. 29-33, Budapest, H-1121, Hungary
| | - Pascal Rusch
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany
| | - Anja Schlosser
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany
| | - Lars F Klepzig
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany
| | - Nadja C Bigall
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstr. 3a, Hannover, 30167, Germany.,Laboratory of Nano and Quantum Engineering, Leibniz Universität Hannover, Schneiderberg 39, Hannover, 30167, Germany.,Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering - Innovation Across Disciplines), Leibniz Universität Hannover, Hannover, 30167, Germany
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4
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Ha SK, Shcherbakov-Wu W, Powers ER, Paritmongkol W, Tisdale WA. Power-Dependent Photoluminescence Efficiency in Manganese-Doped 2D Hybrid Perovskite Nanoplatelets. ACS NANO 2021; 15:20527-20538. [PMID: 34793677 DOI: 10.1021/acsnano.1c09103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Substitutional metal doping is a powerful strategy for manipulating the emission spectra and excited state dynamics of semiconductor nanomaterials. Here, we demonstrate the synthesis of colloidal manganese (Mn2+)-doped organic-inorganic hybrid perovskite nanoplatelets (chemical formula: L2[APb1-xMnxBr3]n-1Pb1-xMnxBr4; L, butylammonium; A, methylammonium or formamidinium; n (= 1 or 2), number of Pb1-xMnxBr64- octahedral layers in thickness) via a ligand-assisted reprecipitation method. Substitutional doping of manganese for lead introduces bright (approaching 100% efficiency) and long-lived (>500 μs) midgap Mn2+ atomic states, and the doped nanoplatelets exhibit dual emission from both the band edge and the dopant state. Photoluminescence quantum yields and band-edge-to-Mn intensity ratios exhibit strong excitation power dependence, even at a very low incident intensity (<100 μW/cm2). Surprisingly, we find that the saturation of long-lived Mn2+ dopant sites cannot explain our observation. Instead, we propose an alternative mechanism involving the cross-relaxation of long-lived Mn-site excitations by freely diffusing band-edge excitons. We formulate a kinetic model based on this cross-relaxation mechanism that quantitatively reproduces all of the experimental observations and validate the model using time-resolved absorption and emission spectroscopy. Finally, we extract a concentration-normalized microscopic rate constant for band edge-to-dopant excitation transfer that is ∼10× faster in methylammonium-containing nanoplatelets than in formamidinium-containing nanoplatelets. This work provides fundamental insight into the interaction of mobile band edge excitons with localized dopant sites in 2D semiconductors and expands the toolbox for manipulating light emission in perovskite nanomaterials.
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Affiliation(s)
- Seung Kyun Ha
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Wenbi Shcherbakov-Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Eric R Powers
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Watcharaphol Paritmongkol
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - William A Tisdale
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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5
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Rtimi S, Kiwi J, Nadtochenko V. Photo-induced environmental remediation, biomedical imaging, and microbial inactivation by Mn-doped semiconductors: critical issues. Curr Opin Chem Eng 2021. [DOI: 10.1016/j.coche.2021.100731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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6
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Mia S, Varapragasam SJP, Baride A, Balasanthiran C, Balasubramanian B, Rioux RM, Hoefelmeyer JD. Diffusion doping of cobalt in rod-shape anatase TiO 2 nanocrystals leads to antiferromagnetism. NANOSCALE ADVANCES 2020; 2:4853-4862. [PMID: 36132911 PMCID: PMC9417846 DOI: 10.1039/d0na00640h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/31/2020] [Indexed: 06/16/2023]
Abstract
Cobalt(ii) ions were adsorbed to the surface of rod-shape anatase TiO2 nanocrystals and subsequently heated to promote ion diffusion into the nanocrystal. After removal of any remaining surface bound cobalt, a sample consisting of strictly cobalt-doped TiO2 was obtained and characterized with powder X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, SQUID magnetometry, and inductively-coupled plasma atomic emission spectroscopy. The nanocrystal morphology was unchanged in the process and no new crystal phases were detected. The concentration of cobalt in the doped samples linearly correlates with the initial loading of cobalt(ii) ions on the nanocrystal surface. Thin films of the cobalt doped TiO2 nanocrystals were prepared on indium-tin oxide coated glass substrate, and the electrical conductivity increased with the concentration of doped cobalt. Magnetic measurements of the cobalt-doped TiO2 nanocrystals reveal paramagnetic behavior at room temperature, and antiferromagnetic interactions between Co ions at low temperatures. Antiferromagnetism is atypical for cobalt-doped TiO2 nanocrystals, and is proposed to arise from interstitial doping that may be favored by the diffusional doping mechanism.
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Affiliation(s)
- Shahzahan Mia
- Department of Chemistry, University of South Dakota 414 E. Clark St. Vermillion SD 57069 USA
| | | | - Aravind Baride
- Department of Chemistry, University of South Dakota 414 E. Clark St. Vermillion SD 57069 USA
| | - Choumini Balasanthiran
- Department of Chemical Engineering, The Pennsylvania State University 22 Chemical Biomedical Engineering Building University Park Pennsylvania 16802-4400 USA
| | - Balamurugan Balasubramanian
- Nebraska Center for Materials and Nanoscience, Department of Physics and Astronomy, University of Nebraska Lincoln NE 68588-0299 USA
| | - Robert M Rioux
- Department of Chemical Engineering, The Pennsylvania State University 22 Chemical Biomedical Engineering Building University Park Pennsylvania 16802-4400 USA
- Department of Chemistry, The Pennsylvania State University 22 Chemical Biomedical Engineering Building University Park Pennsylvania 16802-4400 USA
| | - James D Hoefelmeyer
- Department of Chemistry, University of South Dakota 414 E. Clark St. Vermillion SD 57069 USA
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7
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Tarasek S, Chou WC, Fan WC, Thomay T. Excitation power dependent Coulomb induced recombination dynamics in magnetically doped type-II quantum dots. NANO EXPRESS 2020. [DOI: 10.1088/2632-959x/ab86d9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
We observe that the wavefunction overlap of the carriers in type-II quantum dots (QDs) can be controlled by magnetic doping and strongly depends on the excitation power density. We study two different II-VI magnetic systems; ZnTe/(Zn, Mn)Se QDs with magnetic dopants in the matrix surrounding the dots, and (Zn, Mn)Te/ZnSe QDs doped in the dot core. Both magnetic systems, regardless of the location of the dopant magnetic ions, show a stark contrast in their emission with high excitation power densities (P
ex) when compared to nonmagnetic ZnTe/ZnSe QDs. Using time-resolved photoluminescence (TRPL), we observe a saturation in the blue shift for the magnetic systems at a lower P
ex, while additionally exhibiting a limited lifetime shortening over the entire range of P
ex, when compared to the nonmagnetic QDs. The results for the two magnetic systems are very similar, showing no dependence on the location of the magnetic impurities. This suggests that the behavior observed is an effect of the magnetic polaron on the band bending in the high P
ex regime. The ability to use magnetic ions to quickly saturate the charge concentration and control band bending in QDs could potentially aid in optimizing optoelectronic devices which are sensitive to high charge variations.
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8
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Grating Metamaterials Based on CdTe/CdMgTe Quantum Wells as Terahertz Detectors for High Magnetic Field Applications. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10082807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cyclotron and magnetoplasmon resonances were studied at 2 K in grating metamaterials fabricated on wafers with one or two modulation doped CdTe/CdMgTe quantum wells. The gratings (with the period varied between 2 μ m and 8 μ m) were prepared with an electron beam lithography either by etching or by evaporation of Au. The gratings were studied with an atomic force microscope which revealed a correlation between the depth and width of etched grooves at a constant time of etching. The sharpest resonances observed are due to excitation of magnetoplasmon in the case of Au gratings on a wafer with one quantum well. Etched samples with two quantum wells showed the strongest tuneability of magnetoplasmon resonances with the period of the grating and illumination with white light. We showed that the samples studied can be used as resonant or quasi-resonant terahertz detectors tuneable with magnetic field and white light.
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9
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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] [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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10
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Bogucki A, Zinkiewicz Ł, Grzeszczyk M, Pacuski W, Nogajewski K, Kazimierczuk T, Rodek A, Suffczyński J, Watanabe K, Taniguchi T, Wasylczyk P, Potemski M, Kossacki P. Ultra-long-working-distance spectroscopy of single nanostructures with aspherical solid immersion microlenses. LIGHT, SCIENCE & APPLICATIONS 2020; 9:48. [PMID: 32257179 PMCID: PMC7101340 DOI: 10.1038/s41377-020-0284-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/25/2020] [Accepted: 03/05/2020] [Indexed: 06/08/2023]
Abstract
In light science and applications, equally important roles are played by efficient light emitters/detectors and by the optical elements responsible for light extraction and delivery. The latter should be simple, cost effective, broadband, versatile and compatible with other components of widely desired micro-optical systems. Ideally, they should also operate without high-numerical-aperture optics. Here, we demonstrate that all these requirements can be met with elliptical microlenses 3D printed on top of light emitters. Importantly, the microlenses we propose readily form the collected light into an ultra-low divergence beam (half-angle divergence below 1°) perfectly suited for ultra-long-working-distance optical measurements (600 mm with a 1-inch collection lens), which are not accessible to date with other spectroscopic techniques. Our microlenses can be fabricated on a wide variety of samples, including semiconductor quantum dots and fragile van der Waals heterostructures made of novel two-dimensional materials, such as monolayer and few-layer transition metal dichalcogenides.
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Affiliation(s)
- Aleksander Bogucki
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Łukasz Zinkiewicz
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | | | - Wojciech Pacuski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Karol Nogajewski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Tomasz Kazimierczuk
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Aleksander Rodek
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Jan Suffczyński
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 Japan
| | - Piotr Wasylczyk
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - Marek Potemski
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA, avenue des Martyrs 25, 38042 Grenoble, France
| | - Piotr Kossacki
- Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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11
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Lorenz S, Erickson CS, Riesner M, Gamelin DR, Fainblat R, Bacher G. Directed Exciton Magnetic Polaron Formation in a Single Colloidal Mn 2+:CdSe/CdS Quantum Dot. NANO LETTERS 2020; 20:1896-1906. [PMID: 31999124 DOI: 10.1021/acs.nanolett.9b05136] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
One of the most prominent signatures of transition-metal doping in colloidal nanocrystals is the formation of charge carrier-induced magnetization of the dopant spin sublattice, called exciton magnetic polaron (EMP). Understanding the direction of EMP formation, however, is still a major obstacle. Here, we present a series of temperature-dependent photoluminescence studies on single colloidal Mn2+:CdSe/CdS core/shell quantum dots (QDs) performed in a vector magnetic field providing a unique insight into the interaction between individual excitons and numerous magnetic impurities. The energy of the QD emission and its full width at half-maximum are controlled by the interplay of EMP formation and statistical magnetic fluctuations, in excellent agreement with theory. Most important, we give the first direct demonstration that anisotropy effects-hypothesized for more than a decade-dominate the direction of EMP formation. Our findings reveal a pathway for directing the orientation of optically induced magnetization in colloidal nanocrystals.
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Affiliation(s)
- Severin Lorenz
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Christian S Erickson
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Maurizio Riesner
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University of Duisburg-Essen, Bismarckstr. 81, Duisburg 47057 Germany
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12
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Rodek A, Kazimierczuk T, Bogucki A, Smoleński T, Pacuski W, Kossacki P. Readout of a dopant spin in the anisotropic quantum dot with a single magnetic ion. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:455301. [PMID: 31323648 DOI: 10.1088/1361-648x/ab33d9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Owing to exchange interaction between the exciton and magnetic ion, a quantum dot embedding a single magnetic ion is a great platform for optical control of individual spin. In particular, a quantum dot provides strong and sharp optical transitions, which give experimental access to spin states of an individual magnetic ion. We show, however, that physics of quantum dot excitons also complicate spin readout and optical spin manipulation in such a system. This is due to electron-hole exchange interaction in anisotropic quantum dots, which affects the polarisation of the emission lines. One of the consequences is that the intensity of spectral lines in a single spectrum are not simply proportional to the population of various spin states of magnetic ion. In order to provide a solution of the above problem, we present a method of extracting both the spin polarisation degree of a neutral exciton and magnetic dopant inside a semiconductor quantum dot in an external magnetic field. Our approach is experimentally verified on a system of CdSe/ZnSe quantum dot containing a single Fe2+ ion. Both the resonant and non-resonant excitation regimes are explored resulting in a record high optical orientation efficiency of dopant spin in the former case. The proposed solutions can be easily expanded to any other system of quantum dots containing magnetic dopants.
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Affiliation(s)
- A Rodek
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
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13
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Parobek D, Qiao T, Son DH. Energetic hot electrons from exciton-to-hot electron upconversion in Mn-doped semiconductor nanocrystals. J Chem Phys 2019; 151:120901. [PMID: 31575181 DOI: 10.1063/1.5119398] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Generation of hot electrons and their utilization in photoinduced chemical processes have been the subjects of intense research in recent years mostly exploring hot electrons in plasmonic metal nanostructures created via decay of optically excited plasmon. Here, we present recent progress made in generation and utilization of a different type of hot electrons produced via biphotonic exciton-to-hot electron "upconversion" in Mn-doped semiconductor nanocrystals. Compared to the plasmonic hot electrons, those produced via biphotonic upconversion in Mn-doped semiconductor nanocrystals possess much higher energy, enabling more efficient long-range electron transfer across the high energy barrier. They can even be ejected above the vacuum level creating photoelectrons, which can possibly produce solvated electrons. Despite the biphotonic nature of the upconversion process, hot electrons can be generated with weak cw excitation equivalent to the concentrated solar radiation without requiring intense or high-energy photons. This perspective reviews recent work elucidating the mechanism of generating energetic hot electrons in Mn-doped semiconductor nanocrystals, detection of these hot electrons as photocurrent or photoelectron emission, and their utilization in chemical processes such as photocatalysis. New opportunities that the energetic hot electrons can open by creating solvated electrons, which can be viewed as the longer-lived and mobile version of hot electrons more useful for chemical processes, and the challenges in practical utilization of energetic hot electrons are also discussed.
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Affiliation(s)
- David Parobek
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Tian Qiao
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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14
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Yang J, Muckel F, Choi BK, Lorenz S, Kim IY, Ackermann J, Chang H, Czerney T, Kale VS, Hwang SJ, Bacher G, Hyeon T. Co 2+-Doping of Magic-Sized CdSe Clusters: Structural Insights via Ligand Field Transitions. NANO LETTERS 2018; 18:7350-7357. [PMID: 30265545 DOI: 10.1021/acs.nanolett.8b03627] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Magic-sized clusters represent materials with unique properties at the border between molecules and solids and provide important insights into the nanocrystal formation process. However, synthesis, doping, and especially structural characterization become more and more challenging with decreasing cluster size. Herein, we report the successful introduction of Co2+ ions into extremely small-sized CdSe clusters with the intention of using internal ligand field transitions to obtain structural insights. Despite the huge mismatch between the radii of Cd2+ and Co2+ ions (>21%), CdSe clusters can be effectively synthesized with a high Co2+ doping concentration of ∼10%. Optical spectroscopy and mass spectrometry suggest that one or two Co2+ ions are substitutionally embedded into (CdSe)13 clusters, which is known as one of the smallest CdSe clusters. Using magnetic circular dichroism spectroscopy on the intrinsic ligand field transitions between the different 3d orbitals of the transition metal dopants, we demonstrate that the Co2+ dopants are embedded on pseudotetrahedral selenium coordinated sites despite the limited number of atoms in the clusters. A significant shortening of Co-Se bond lengths compared to bulk or nanocrystals is observed, which results in the metastability of Co2+ doping. Our results not only extend the doping chemistry of magic-sized semiconductor nanoclusters, but also suggest an effective method to characterize the local structure of these extremely small-sized clusters.
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Affiliation(s)
- Jiwoong Yang
- Center for Nanoparticle Research , Institute for Basic Science (IBS) , Seoul 08826 , Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Franziska Muckel
- Werkstoffe der Elektrotechnik und CENIDE , University Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany
| | - Back Kyu Choi
- Center for Nanoparticle Research , Institute for Basic Science (IBS) , Seoul 08826 , Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Severin Lorenz
- Werkstoffe der Elektrotechnik und CENIDE , University Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany
| | - In Young Kim
- Center for Hybrid Interfacial Chemical Structure (CICS), Department of Chemistry and Nanoscience , Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Julia Ackermann
- Werkstoffe der Elektrotechnik und CENIDE , University Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany
| | - Hogeun Chang
- Center for Nanoparticle Research , Institute for Basic Science (IBS) , Seoul 08826 , Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Tamara Czerney
- Werkstoffe der Elektrotechnik und CENIDE , University Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany
| | - Vinayak S Kale
- Center for Nanoparticle Research , Institute for Basic Science (IBS) , Seoul 08826 , Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
| | - Seong-Ju Hwang
- Center for Hybrid Interfacial Chemical Structure (CICS), Department of Chemistry and Nanoscience , Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik und CENIDE , University Duisburg-Essen , Bismarckstraße 81 , 47057 Duisburg , Germany
| | - Taeghwan Hyeon
- Center for Nanoparticle Research , Institute for Basic Science (IBS) , Seoul 08826 , Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes , Seoul National University , Seoul 08826 , Republic of Korea
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15
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Zhang K, Feng J, Liu H. Synthesis of manganese-doped silver selenide quantum dots with near-infrared photoluminescent and paramagnetic properties. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.06.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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16
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Smoleński T, Cywiński Ł, Kossacki P. Mechanisms of optical orientation of an individual Mn 2+ ion spin in a II-VI quantum dot. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:055303. [PMID: 29315081 DOI: 10.1088/1361-648x/aaa20c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We provide a theoretical description of the optical orientation of a single Mn2+ ion spin under quasi-resonant excitation demonstrated experimentally by Goryca et al (2009 Phys. Rev. Lett. 103 087401). We build and analyze a hierarchy of models by starting with the simplest assumptions (transfer of perfectly spin-polarized excitons from Mn-free dot to the other dot containing a single Mn2+ spin, followed by radiative recombination) and subsequently adding more features, such as spin relaxation of electrons and holes. Particular attention is paid to the role of the influx of the dark excitons and the process of biexciton formation, which are shown to contribute significantly to the orientation process in the quasi-resonant excitation case. Analyzed scenarios show how multiple features of the excitonic complexes in magnetically-doped quantum dots, such as the values of exchange integrals, spin relaxation times, etc, lead to a plethora of optical orientation processes, characterized by distinct dependencies on light polarization and laser intensity, and occurring on distinct timescales. Comparison with experimental data shows that the correct description of the optical orientation mechanism requires taking into account Mn2+ spin-flip processes occurring not only when the exciton is already in the orbital ground state of the light-emitting dot, but also those that happen during the exciton transfer from high-energy states to the ground state. Inspired by the experimental results on energy relaxation of electrons and holes in nonmagnetic dots, we focus on the process of biexciton creation allowed by mutual spin-flip of an electron and the Mn2+ spin, and we show that by including it in the model, we obtain good qualitative and quantitative agreement with the experimental data on quasi-resonantly driven Mn2+ spin orientation.
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Affiliation(s)
- T Smoleński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
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17
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Pradhan N, Das Adhikari S, Nag A, Sarma DD. Luminescence, Plasmonic, and Magnetic Properties of Doped Semiconductor Nanocrystals. Angew Chem Int Ed Engl 2017; 56:7038-7054. [DOI: 10.1002/anie.201611526] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/18/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Narayan Pradhan
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 India
| | - Samrat Das Adhikari
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 India
| | - Angshuman Nag
- Department of Chemistry and Centre for Energy Science; Indian Institute of Science Education and Research, IISER; Pune 411008 India
| | - D. D. Sarma
- Solid State and Structural Chemistry Unit; Indian Institute of Science; Bengaluru 560012 India
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18
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Pradhan N, Das Adhikari S, Nag A, Sarma DD. Dotierte Halbleiter-Nanokristalle: Lumineszenz, plasmonische und magnetische Eigenschaften. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611526] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Narayan Pradhan
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 Indien
| | - Samrat Das Adhikari
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 Indien
| | - Angshuman Nag
- Department of Chemistry and Centre for Energy Science; Indian Institute of Science Education and Research, IISER; Pune 411008 Indien
| | - D. D. Sarma
- Solid State and Structural Chemistry Unit; Indian Institute of Science; Bengaluru 560012 Indien
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19
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Rice WD, Liu W, Pinchetti V, Yakovlev DR, Klimov VI, Crooker SA. Direct Measurements of Magnetic Polarons in Cd 1-xMn xSe Nanocrystals from Resonant Photoluminescence. NANO LETTERS 2017; 17:3068-3075. [PMID: 28388078 DOI: 10.1021/acs.nanolett.7b00421] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In semiconductors, quantum confinement can greatly enhance the interaction between band carriers (electrons and holes) and dopant atoms. One manifestation of this enhancement is the increased stability of exciton magnetic polarons in magnetically doped nanostructures. In the limit of very strong 0D confinement that is realized in colloidal semiconductor nanocrystals, a single exciton can exert an effective exchange field Bex on the embedded magnetic dopants that exceeds several tesla. Here we use the very sensitive method of resonant photoluminescence (PL) to directly measure the presence and properties of exciton magnetic polarons in colloidal Cd1-xMnxSe nanocrystals. Despite small Mn2+ concentrations (x = 0.4-1.6%), large polaron binding energies up to ∼26 meV are observed at low temperatures via the substantial Stokes shift between the pump laser and the resonant PL maximum, indicating nearly complete alignment of all Mn2+ spins by Bex. Temperature and magnetic field-dependent studies reveal that Bex ≈ 10 T in these nanocrystals, in good agreement with theoretical estimates. Further, the emission line widths provide direct insight into the statistical fluctuations of the Mn2+ spins. These resonant PL studies provide detailed insight into collective magnetic phenomena, especially in lightly doped nanocrystals where conventional techniques such as nonresonant PL or time-resolved PL provide ambiguous results.
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Affiliation(s)
- W D Rice
- Department of Physics and Astronomy, University of Wyoming , Laramie, Wyoming 82071, United States
| | | | - V Pinchetti
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via Cozzi 55, IT-20125 Milano, Italy
| | - D R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund , D-44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg, Russia
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20
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Yang J, Muckel F, Baek W, Fainblat R, Chang H, Bacher G, Hyeon T. Chemical Synthesis, Doping, and Transformation of Magic-Sized Semiconductor Alloy Nanoclusters. J Am Chem Soc 2017; 139:6761-6770. [DOI: 10.1021/jacs.7b02953] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Jiwoong Yang
- Center
for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Franziska Muckel
- Werkstoffe
der Elektrotechnik und CENIDE, University Duisburg-Essen, Bismarckstraße
81, 47057 Duisburg, Germany
| | - Woonhyuk Baek
- Center
for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Rachel Fainblat
- Center
for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
- Werkstoffe
der Elektrotechnik und CENIDE, University Duisburg-Essen, Bismarckstraße
81, 47057 Duisburg, Germany
| | - Hogeun Chang
- Center
for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Gerd Bacher
- Werkstoffe
der Elektrotechnik und CENIDE, University Duisburg-Essen, Bismarckstraße
81, 47057 Duisburg, Germany
| | - Taeghwan Hyeon
- Center
for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
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21
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Wojnar P, Płachta J, Kret S, Kaleta A, Zaleszczyk W, Szymura M, Wiater M, Baczewski LT, Pietruczik A, Karczewski G, Wojtowicz T, Kossut J. Growth and optical investigations of high quality individual CdTe/(Cd,Mg)Te core/shell nanowires. NANOTECHNOLOGY 2017; 28:045207. [PMID: 28000610 DOI: 10.1088/1361-6528/28/4/045207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.
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Affiliation(s)
- P Wojnar
- Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
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22
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Fainblat R, Barrows CJ, Hopmann E, Siebeneicher S, Vlaskin VA, Gamelin DR, Bacher G. Giant Excitonic Exchange Splittings at Zero Field in Single Colloidal CdSe Quantum Dots Doped with Individual Mn 2+ Impurities. NANO LETTERS 2016; 16:6371-6377. [PMID: 27646931 DOI: 10.1021/acs.nanolett.6b02775] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Replacing a single atom of a host semiconductor nanocrystal with a functional dopant can introduce completely new properties potentially valuable for "solotronic" information-processing applications. Here, we report successful doping of colloidal CdSe quantum dots with a very small number of manganese ions-down to the ultimate limit of one. Single-particle spectroscopy reveals spectral fingerprints of the spin-spin interactions between individual dopants and quantum-dot excitons. Spectrally well-resolved emission peaks are observed that can be related to the discrete spin projections of individual Mn2+ ions. In agreement with theoretical predictions, the exchange splittings are enhanced by more than an order of magnitude in these quantum dots compared to their epitaxial counterparts, opening a path for solotronic applications at elevated temperatures.
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Affiliation(s)
- Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstr. 81, Duisburg, 47057 Germany
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Charles J Barrows
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Eric Hopmann
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstr. 81, Duisburg, 47057 Germany
| | - Simon Siebeneicher
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstr. 81, Duisburg, 47057 Germany
| | - Vladmir A Vlaskin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstr. 81, Duisburg, 47057 Germany
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23
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Muckel F, Yang J, Lorenz S, Baek W, Chang H, Hyeon T, Bacher G, Fainblat R. Digital Doping in Magic-Sized CdSe Clusters. ACS NANO 2016; 10:7135-41. [PMID: 27420556 DOI: 10.1021/acsnano.6b03348] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Magic-sized semiconductor clusters represent an exciting class of materials located at the boundary between quantum dots and molecules. It is expected that replacing single atoms of the host crystal with individual dopants in a one-by-one fashion can lead to unique modifications of the material properties. Here, we demonstrate the dependence of the magneto-optical response of (CdSe)13 clusters on the discrete number of Mn(2+) ion dopants. Using time-of-flight mass spectrometry, we are able to distinguish undoped, monodoped, and bidoped cluster species, allowing for an extraction of the relative amount of each species for a specific average doping concentration. A giant magneto-optical response is observed up to room temperature with clear evidence that exclusively monodoped clusters are magneto-optically active, whereas the Mn(2+) ions in bidoped clusters couple antiferromagnetically and are magneto-optically passive. Mn(2+)-doped clusters therefore represent a system where magneto-optical functionality is caused by solitary dopants, which might be beneficial for future solotronic applications.
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Affiliation(s)
- Franziska Muckel
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstraße 81, 47057 Duisburg, Germany
| | - Jiwoong Yang
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University , Seoul 08826, Republic of Korea
| | - Severin Lorenz
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstraße 81, 47057 Duisburg, Germany
| | - Woonhyuk Baek
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University , Seoul 08826, Republic of Korea
| | - Hogeun Chang
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University , Seoul 08826, Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University , Seoul 08826, Republic of Korea
| | - Gerd Bacher
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstraße 81, 47057 Duisburg, Germany
| | - Rachel Fainblat
- Werkstoffe der Elektrotechnik and CENIDE, University Duisburg-Essen , Bismarckstraße 81, 47057 Duisburg, Germany
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University , Seoul 08826, Republic of Korea
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24
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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. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 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] [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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25
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Balanta MAG, Brasil MJSP, Iikawa F, Mendes UC, Brum JA, Danilov YA, Dorokhin MV, Vikhrova OV, Zvonkov BN. Optically controlled spin-polarization memory effect on Mn delta-doped heterostructures. Sci Rep 2016; 6:24537. [PMID: 27080310 PMCID: PMC4832231 DOI: 10.1038/srep24537] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 03/31/2016] [Indexed: 11/24/2022] Open
Abstract
We investigated the dynamics of the interaction between spin-polarized photo-created carriers and Mn ions on InGaAs/GaAs: Mn structures. The carriers are confined in an InGaAs quantum well and the Mn ions come from a Mn delta-layer grown at the GaAs barrier close to the well. Even though the carriers and the Mn ions are spatially separated, the interaction between them is demonstrated by time-resolved spin-polarized photoluminescence measurements. Using a pre-pulse laser excitation with an opposite circular-polarization clearly reduces the polarization degree of the quantum-well emission for samples where a strong magnetic interaction is observed. The results demonstrate that the Mn ions act as a spin-memory that can be optically controlled by the polarization of the photocreated carriers. On the other hand, the spin-polarized Mn ions also affect the spin-polarization of the subsequently created carriers as observed by their spin relaxation time. These effects fade away with increasing time delays between the pulses as well as with increasing temperatures.
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Affiliation(s)
- M A G Balanta
- Instituto de Física "Gleb Wataghin", Unicamp, 13083-859 Campinas, SP, Brazil.,Departamento de Física, Universidade Federal de São Carlos, CP 676, São Carlos, SP 13565-905, Brazil
| | - M J S P Brasil
- Instituto de Física "Gleb Wataghin", Unicamp, 13083-859 Campinas, SP, Brazil
| | - F Iikawa
- Instituto de Física "Gleb Wataghin", Unicamp, 13083-859 Campinas, SP, Brazil
| | - Udson C Mendes
- Instituto de Física "Gleb Wataghin", Unicamp, 13083-859 Campinas, SP, Brazil.,Laboratoire Pierre Aigrain, École Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
| | - J A Brum
- Instituto de Física "Gleb Wataghin", Unicamp, 13083-859 Campinas, SP, Brazil
| | - Yu A Danilov
- Research Institute, State University Nizhny Novgorod, Russia
| | - M V Dorokhin
- Research Institute, State University Nizhny Novgorod, Russia
| | - O V Vikhrova
- Research Institute, State University Nizhny Novgorod, Russia
| | - B N Zvonkov
- Research Institute, State University Nizhny Novgorod, Russia
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26
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Rice WD, Liu W, Baker TA, Sinitsyn NA, Klimov VI, Crooker SA. Revealing giant internal magnetic fields due to spin fluctuations in magnetically doped colloidal nanocrystals. NATURE NANOTECHNOLOGY 2016; 11:137-142. [PMID: 26595331 DOI: 10.1038/nnano.2015.258] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
Strong quantum confinement in semiconductors can compress the wavefunctions of band electrons and holes to nanometre-scale volumes, significantly enhancing interactions between themselves and individual dopants. In magnetically doped semiconductors, where paramagnetic dopants (such as Mn(2+), Co(2+) and so on) couple to band carriers via strong sp-d spin exchange, giant magneto-optical effects can therefore be realized in confined geometries using few or even single impurity spins. Importantly, however, thermodynamic spin fluctuations become increasingly relevant in this few-spin limit. In nanoscale volumes, the statistical fluctuations of N spins are expected to generate giant effective magnetic fields Beff, which should dramatically impact carrier spin dynamics, even in the absence of any applied field. Here we directly and unambiguously reveal the large Beff that exist in Mn(2+)-doped CdSe colloidal nanocrystals using ultrafast optical spectroscopy. At zero applied magnetic field, extremely rapid (300-600 GHz) spin precession of photoinjected electrons is observed, indicating Beff ∼ 15 -30 T for electrons. Precession frequencies exceed 2 THz in applied magnetic fields. These signals arise from electron precession about the random fields due to statistically incomplete cancellation of the embedded Mn(2+) moments, thereby revealing the initial coherent dynamics of magnetic polaron formation, and highlighting the importance of magnetization fluctuations on carrier spin dynamics in nanomaterials.
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Affiliation(s)
- William D Rice
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Wenyong Liu
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Thomas A Baker
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Nikolai A Sinitsyn
- Theory Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Victor I Klimov
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Scott A Crooker
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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27
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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] [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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28
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Nelson HD, Bradshaw LR, Barrows CJ, Vlaskin VA, Gamelin DR. Picosecond Dynamics of Excitonic Magnetic Polarons in Colloidal Diffusion-Doped Cd(1-x)Mn(x)Se Quantum Dots. ACS NANO 2015; 9:11177-11191. [PMID: 26417918 DOI: 10.1021/acsnano.5b04719] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Spontaneous magnetization is observed at zero magnetic field in photoexcited colloidal Cd(1-x)Mn(x)Se (x = 0.13) quantum dots (QDs) prepared by diffusion doping, reflecting strong Mn(2+)-exciton exchange coupling. The picosecond dynamics of this phenomenon, known as an excitonic magnetic polaron (EMP), are examined using a combination of time-resolved photoluminescence, magneto-photoluminescence, and Faraday rotation (TRFR) spectroscopies, in conjunction with continuous-wave absorption, magnetic circular dichroism (MCD), and magnetic circularly polarized photoluminescence (MCPL) spectroscopies. The data indicate that EMPs form with random magnetization orientations at zero external field, but their formation can be directed by an external magnetic field. After formation, however, external magnetic fields are unable to reorient the EMPs within the luminescence lifetime, implicating anisotropy in the EMP potential-energy surfaces. TRFR measurements in a transverse magnetic field reveal rapid (<5 ps) spin transfer from excitons to Mn(2+) followed by coherent EMP precession at the Mn(2+) Larmor frequency for over a nanosecond. A dynamical TRFR phase inversion is observed during EMP formation attributed to the large shifts in excitonic absorption energies during spontaneous magnetization. Partial optical orientation of the EMPs by resonant circularly polarized photoexcitation is also demonstrated. Collectively, these results highlight the extraordinary physical properties of colloidal diffusion-doped Cd(1-x)Mn(x)Se QDs that result from their unique combination of strong quantum confinement, large Mn(2+) concentrations, and relatively narrow size distributions. The insights gained from these measurements advance our understanding of spin dynamics and magnetic exchange in colloidal doped semiconductor nanostructures, with potential ramifications for future spin-based information technologies.
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Affiliation(s)
- Heidi D Nelson
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Liam R Bradshaw
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Charles J Barrows
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Vladimir A Vlaskin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
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29
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Barrows CJ, Vlaskin VA, Gamelin DR. Absorption and Magnetic Circular Dichroism Analyses of Giant Zeeman Splittings in Diffusion-Doped Colloidal Cd(1-x)Mn(x)Se Quantum Dots. J Phys Chem Lett 2015; 6:3076-3081. [PMID: 26267205 DOI: 10.1021/acs.jpclett.5b01137] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Impurity ions can transform the electronic, magnetic, or optical properties of colloidal quantum dots. Magnetic impurities introduce strong dopant-carrier exchange coupling that generates giant Zeeman splittings (ΔEZ) of excitonic excited states. To date, ΔEZ in colloidal doped quantum dots has primarily been quantified by analysis of magnetic circular dichroism (MCD) intensities and absorption line widths (σ). Here, we report ΔEZ values detected directly by absorption spectroscopy for the first time in such materials, using colloidal Cd(1-x)Mn(x)Se quantum dots prepared by diffusion doping. A convenient method for decomposing MCD and absorption data into circularly polarized absorption spectra is presented. These data confirm the widely applied MCD analysis in the low-field, high-temperature regime, but also reveal a breakdown at low temperatures and high fields when ΔEZ/σ approaches unity, a situation not previously encountered in doped quantum dots. This breakdown is apparent for the first time here because of the extraordinarily large ΔEZ and small σ achieved by nanocrystal diffusion doping.
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Affiliation(s)
- Charles J Barrows
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Vladimir A Vlaskin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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30
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Electron spin coherence near room temperature in magnetic quantum dots. Sci Rep 2015; 5:10855. [PMID: 26040432 PMCID: PMC4455149 DOI: 10.1038/srep10855] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/07/2015] [Indexed: 11/18/2022] Open
Abstract
We report on an example of confined magnetic ions with long spin coherence near room temperature. This was achieved by confining single Mn2+ spins in colloidal semiconductor quantum dots (QDs) and by dispersing the QDs in a proton-spin free matrix. The controlled suppression of Mn–Mn interactions and minimization of Mn–nuclear spin dipolar interactions result in unprecedentedly long phase memory (TM ~ 8 μs) and spin–lattice relaxation (T1 ~ 10 ms) time constants for Mn2+ ions at T = 4.5 K, and in electron spin coherence observable near room temperature (TM ~ 1 μs).
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31
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Schimpf AM, Rinehart JD, Ochsenbein ST, Gamelin DR. Charge-State Control of Mn(2+) Spin Relaxation Dynamics in Colloidal n-Type Zn1-xMnxO Nanocrystals. J Phys Chem Lett 2015; 6:1748-1753. [PMID: 26263344 DOI: 10.1021/acs.jpclett.5b00621] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Colloidal diluted magnetic semiconductor (DMS) nanocrystals are model systems for studying spin effects in semiconductor nanostructures with relevance to future spin-based information processing technologies. The introduction of excess delocalized charge carriers into such nanocrystals turns on strong dopant-carrier magnetic exchange interactions, with important consequences for the physical properties of these materials. Here, we use pulsed electron paramagnetic resonance (pEPR) spectroscopy to probe the effects of excess conduction band electrons on the spin dynamics of colloidal Mn(2+)-doped ZnO nanocrystals. Mn(2+) spin-lattice relaxation is strongly accelerated by the addition of even one conduction band electron per Zn1-xMnxO nanocrystal, attributable to the introduction of a new exchange-based Mn(2+) spin relaxation pathway. A kinetic model is used to describe the enhanced relaxation rates, yielding new insights into the spin dynamics and electronic structures of these materials with potential ramifications for future applications of DMS nanostructures in spin-based technologies.
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Affiliation(s)
- Alina M Schimpf
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Jeffrey D Rinehart
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Stefan T Ochsenbein
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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32
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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. PHYSICAL REVIEW LETTERS 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] [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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33
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Jakubczyk T, Franke H, Smoleński T, Sciesiek M, Pacuski W, Golnik A, Schmidt-Grund R, Grundmann M, Kruse C, Hommel D, Kossacki P. Inhibition and enhancement of the spontaneous emission of quantum dots in micropillar cavities with radial-distributed Bragg reflectors. ACS NANO 2014; 8:9970-9978. [PMID: 25181393 DOI: 10.1021/nn5017555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a micropillar cavity where nondesired radial emission is inhibited. The photonic confinement in such a structure is improved by implementation of an additional concentric radial-distributed Bragg reflector. Such a reflector increases the reflectivity in all directions perpendicular to the micropillar axis from a typical value of 15-31% to above 98%. An inhibition of the spontaneous emission of off-resonant excitonic states of quantum dots embedded in the microcavity is revealed by time-resolved experiments. It proves a decreased density of photonic states related to unwanted radial leakage of photons out of the micropillar. For on-resonance conditions, we find that the dot emission rate is increased, evidencing the Purcell enhancement of spontaneous emission. The proposed design can increase the efficiency of single-photon sources and bring to micropillar cavities the functionalities based on lengthened decay times.
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Affiliation(s)
- Tomasz Jakubczyk
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw , Hoża 69, 00-681 Warsaw, Poland
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