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Li S, Wang F, Wang Y, Yang J, Wang X, Zhan X, He J, Wang Z. Van der Waals Ferroelectrics: Theories, Materials, and Device Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2301472. [PMID: 37363893 DOI: 10.1002/adma.202301472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/19/2023] [Indexed: 06/28/2023]
Abstract
In recent years, an increasing number of 2D van der Waals (vdW) materials are theory-predicted or laboratory-validated to possess in-plane (IP) and/or out-of-plane (OOP) spontaneous ferroelectric polarization. Due to their dangling-bond-free surfaces, interlayer charge coupling, robust polarization, tunable energy band structures, and compatibility with silicon-based technologies, vdW ferroelectric materials exhibit great promise in ferroelectric memories, neuromorphic computing, nanogenerators, photovoltaic devices, spintronic devices, and so on. Here, the very recent advances in the field of vdW ferroelectrics (FEs) are reviewed. First, theories of ferroelectricity are briefly discussed. Then, a comprehensive summary of the non-stacking vdW ferroelectric materials is provided based on their crystal structures and the emerging sliding ferroelectrics. In addition, their potential applications in various branches/frontier fields are enumerated, with a focus on artificial intelligence. Finally, the challenges and development prospects of vdW ferroelectrics are discussed.
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Affiliation(s)
- Shuhui Li
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Feng Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Yanrong Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Jia Yang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Xinyuan Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Xueying Zhan
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Jun He
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072, P. R. China
| | - Zhenxing Wang
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100190, P. R. China
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2
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Yu Y, Xie L, Pennycook SJ, Bosman M, He J. Strain-induced van der Waals gaps in GeTe revealed by in situ nanobeam diffraction. SCIENCE ADVANCES 2022; 8:eadd7690. [PMID: 36367928 PMCID: PMC9651738 DOI: 10.1126/sciadv.add7690] [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: 07/03/2022] [Accepted: 09/27/2022] [Indexed: 06/16/2023]
Abstract
Ordered germanium vacancies in germanium telluride thermoelectric material are called van der Waals (vdW) gaps, and they are beneficial for the thermoelectric performance of the material. The vdW gaps have been observed by atomic resolution scanning transmission electron microscopy, but their origin remains unclear, which prevents their extensive application in other materials systems. Here, we report that the occurrence of vdW gaps in germanium telluride is mainly driven by strain from the cubic-to-rhombohedral martensitic transition. Direct strain and structural evidence are given here by in situ nanobeam diffraction and in situ transmission electron microscopy observation. Dislocation theory is used to discuss the origin of vdW gaps. Our work here paves the way for self-assembling two-dimensional ordered vacancies, which establishes a previously unidentified degree of freedom to adjust their electronic and thermal properties.
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Affiliation(s)
- Yong Yu
- Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Lin Xie
- Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Stephen J. Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Michel Bosman
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117575, Singapore
| | - Jiaqing He
- Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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3
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Frolov AS, Callaert C, Batuk M, Hadermann J, Volykhov AA, Sirotina AP, Amati M, Gregoratti L, Yashina LV. Nanoscale phase separation in the oxide layer at GeTe (111) surfaces. NANOSCALE 2022; 14:12918-12927. [PMID: 36043425 DOI: 10.1039/d2nr02261c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
As a semiconductor ferroelectric, GeTe has become a focus of renewed attention due to the recent discovery of giant Rashba splitting. It already has a wide range of applications, from thermoelectricity to data storage. Its stability in ambient air, as well as the structure and properties of an oxide layer, define the processing media for device production and operation. Here, we studied a reaction between the GeTe (111) surface and molecular oxygen for crystals having solely inversion domains. We evaluated the reaction kinetics both ex situ and in situ using NAP XPS. The structure of the oxide layer is extensively discussed, where, according to HAADF-STEM and STEM-EDX, nanoscale phase separation of GeO2 and Te is observed, which is unusual for semiconductors. We believe that such behaviour is closely related to the ferroelectric properties and the domain structure of GeTe.
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Affiliation(s)
- Alexander S Frolov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia.
- N.N. Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
| | - Carolien Callaert
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Maria Batuk
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Joke Hadermann
- EMAT, Department of Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
| | - Andrey A Volykhov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia.
- Institute of General and Inorganic Chemistry RAS, Leninsky Avenue 31, 119991 Moscow, Russia
| | - Anna P Sirotina
- N.N. Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
- Institute of Nanotechnology of Microelectronics RAS, Nagatinskaya str., 16A/11, 115487 Moscow, Russia
| | - Matteo Amati
- Elettra - Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Luca Gregoratti
- Elettra - Sincrotrone Trieste S.C.p.A., Area Science Park, I-34012 Basovizza, Trieste, Italy
| | - Lada V Yashina
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia.
- N.N. Semenov Federal Research Center for Chemical Physics, Kosygina Street 4, 119991 Moscow, Russia
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4
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Clark OJ, Wadgaonkar I, Freyse F, Springholz G, Battiato M, Sánchez-Barriga J. Ultrafast Thermalization Pathways of Excited Bulk and Surface States in the Ferroelectric Rashba Semiconductor GeTe. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2200323. [PMID: 35388556 DOI: 10.1002/adma.202200323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/22/2022] [Indexed: 06/14/2023]
Abstract
A large Rashba effect is essential for future applications in spintronics. Particularly attractive is understanding and controlling nonequilibrium properties of ferroelectric Rashba semiconductors. Here, time- and angle-resolved photoemission is utilized to access the ultrafast dynamics of bulk and surface transient Rashba states after femtosecond optical excitation of GeTe. A complex thermalization pathway is observed, wherein three different timescales can be clearly distinguished: intraband thermalization, interband equilibration, and electronic cooling. These dynamics exhibit an unconventional temperature dependence: while the cooling phase speeds up with increasing sample temperature, the opposite happens for interband thermalization. It is demonstrated how, due to the Rashba effect, an interdependence of these timescales on the relative strength of both electron-electron and electron-phonon interactions is responsible for the counterintuitive temperature dependence, with spin-selection constrained interband electron-electron scatterings found both to dominate dynamics away from the Fermi level, and to weaken with increasing temperature. These findings are supported by theoretical calculations within the Boltzmann approach explicitly showing the opposite behavior of all relevant electron-electron and electron-phonon scattering channels with temperature, thus confirming the microscopic mechanism of the experimental findings. The present results are important for future applications of ferroelectric Rashba semiconductors and their excitations in ultrafast spintronics.
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Affiliation(s)
- Oliver J Clark
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, 12489, Berlin, Germany
| | - Indrajit Wadgaonkar
- Nanyang Technological University, Nanyang Link 21, Singapore, 637371, Singapore
| | - Friedrich Freyse
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, 12489, Berlin, Germany
- Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany
| | - Gunther Springholz
- Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - Marco Battiato
- Nanyang Technological University, Nanyang Link 21, Singapore, 637371, Singapore
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Str. 15, 12489, Berlin, Germany
- IMDEA Nanoscience, C/ Faraday 9, Campus de Cantoblanco, Madrid, 28049, Spain
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5
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Zeng T, He H, Guan H, Yuan R, Liu X, Zhang C. Tunable Hollow Nanoreactors for In Situ Synthesis of GeP Electrodes towards High-Performance Sodium Ion Batteries. Angew Chem Int Ed Engl 2021; 60:12103-12108. [PMID: 33689206 DOI: 10.1002/anie.202102954] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Indexed: 01/19/2023]
Abstract
The practical application of germanium phosphide (GeP) in battery systems is seriously impeded referring to the sluggish reaction kinetics and severe volume change. Nanostructure design that elaborately resolves the above issues is highly desired but still remains a big challenge. Herein, unique hollow nanoreactors assembled with nitrogen-doped carbon networks for in situ synthesis of the GeP electrodes are proposed for the first time. Such nanoreactors form a self-supported conductive network, ensuring sufficient electrolyte infiltration and fast electron transport. They restrain crystal growth and accommodate the volume expansion of GeP simultaneously. Reaction kinetics and confinement effect are optimized through nanoreactor size regulation. The optimized GeP electrode has high reversible capacities and outstanding cyclability and rate performance for sodium storage, outperforming most previously reported phosphides.
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Affiliation(s)
- Tianbiao Zeng
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Hanna He
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Huibin Guan
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Ruoxin Yuan
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Xingang Liu
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
| | - Chuhong Zhang
- State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, 610065, China
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6
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Zeng T, He H, Guan H, Yuan R, Liu X, Zhang C. Tunable Hollow Nanoreactors for In Situ Synthesis of GeP Electrodes towards High‐Performance Sodium Ion Batteries. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202102954] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Tianbiao Zeng
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Hanna He
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Huibin Guan
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Ruoxin Yuan
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Xingang Liu
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
| | - Chuhong Zhang
- State Key Laboratory of Polymer Materials Engineering Polymer Research Institute Sichuan University Chengdu 610065 China
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7
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Zhussupbekov K, Walshe K, Walls B, Ionov A, Bozhko SI, Ksenz A, Mozhchil RN, Zhussupbekova A, Fleischer K, Berman S, Zhilyaev I, O’Regan DD, Shvets IV. Surface Modification and Subsequent Fermi Density Enhancement of Bi(111). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:5549-5558. [PMID: 34276852 PMCID: PMC8279637 DOI: 10.1021/acs.jpcc.0c07345] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/24/2021] [Indexed: 06/13/2023]
Abstract
Defects introduced to the surface of Bi(111) break the translational symmetry and modify the surface states locally. We present a theoretical and experimental study of the 2D defects on the surface of Bi(111) and the states that they induce. Bi crystals cleaved in ultrahigh vacuum (UHV) at low temperature (110 K) and the resulting ion-etched surface are investigated by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy (UPS), and scanning tunneling microscopy (STM) as well as spectroscopy (STS) techniques in combination with density functional theory (DFT) calculations. STS measurements of cleaved Bi(111) reveal that a commonly observed bilayer step edge has a lower density of states (DOS) around the Fermi level as compared to the atomic-flat terrace. Following ion bombardment, the Bi(111) surface reveals anomalous behavior at both 110 and 300 K: Surface periodicity is observed by LEED, and a significant increase in the number of bilayer step edges and energetically unfavorable monolayer steps is observed by STM. It is suggested that the newly exposed monolayer steps and the type A bilayer step edges result in an increase to the surface Fermi density as evidenced by UPS measurements and the Kohn-Sham DOS. These states appear to be thermodynamically stable under UHV conditions.
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Affiliation(s)
- Kuanysh Zhussupbekov
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Killian Walshe
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Brian Walls
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Andrei Ionov
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Sergei I. Bozhko
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Andrei Ksenz
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Rais N. Mozhchil
- Institute
of Solid State Physics, Russian Academy
of Sciences, Chernogolovka, Russia
| | - Ainur Zhussupbekova
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Karsten Fleischer
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- School
of Physical Sciences, Dublin City University, Dublin 9, Ireland
| | - Samuel Berman
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
| | - Ivan Zhilyaev
- Institute
of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences, Chernogolovka, Russia
| | - David D. O’Regan
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
- AMBER,
the SFI Research Centre for Advanced Materials and BioEngineering
Research, Dublin 2, Ireland
| | - Igor V. Shvets
- School
of Physics and Centre for Research on Adaptive Nanostructures and
Nanodevices (CRANN), Trinity College Dublin, Dublin 2, Ireland
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8
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Zhussupbekov K, Cullen CP, Zhussupbekova A, Shvets IV, Duesberg GS, McEvoy N, Ó Coileáin C. Electronic and structural characterisation of polycrystalline platinum disulfide thin films. RSC Adv 2020; 10:42001-42007. [PMID: 35516737 PMCID: PMC9057923 DOI: 10.1039/d0ra07405e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/02/2020] [Indexed: 12/15/2022] Open
Abstract
We employ a combination of scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS) to investigate the properties of layered PtS2, synthesised via thermally assisted conversion (TAC) of a metallic Pt thin film. STM measurements reveal the 1T crystal structure of PtS2, and the lattice constant is determined to be 3.58 ± 0.03 Å. STS allowed the electronic structure of individual PtS2 crystallites to be directly probed and a bandgap of ∼1.03 eV was determined for a 3.8 nm thick flake at liquid nitrogen temperature. These findings substantially expand understanding of the atomic and electronic structure of PtS2 and indicate that STM is a powerful tool capable of locally probing non-uniform polycrystalline films, such as those produced by TAC. Prior to STM/STS measurements the quality of synthesised TAC PtS2 was analysed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. These results are of relevance to applications-focussed studies centred on PtS2 and may inform future efforts to optimise the synthesis conditions for thin film PtS2. Semiconducting thin-film polycrystalline PtS2 is characterised by atomically resolved scanning tunnelling microscopy and spectroscopy.![]()
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Affiliation(s)
- Kuanysh Zhussupbekov
- School of Physics, Trinity College Dublin Dublin 2 Ireland .,AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland
| | - Conor P Cullen
- AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland .,School of Chemistry, Trinity College Dublin Dublin 2 D02 PN40 Ireland
| | - Ainur Zhussupbekova
- School of Physics, Trinity College Dublin Dublin 2 Ireland .,AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland
| | - Igor V Shvets
- School of Physics, Trinity College Dublin Dublin 2 Ireland .,AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland
| | - Georg S Duesberg
- Institute of Physics, EIT 2, Faculty of Electrical Engineering and Information Technology, Universität der Bundeswehr München 85579 Neubiberg Germany
| | - Niall McEvoy
- AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland .,School of Chemistry, Trinity College Dublin Dublin 2 D02 PN40 Ireland
| | - Cormac Ó Coileáin
- AMBER Centre, CRANN Institute, Trinity College Dublin Dublin 2 Ireland .,School of Chemistry, Trinity College Dublin Dublin 2 D02 PN40 Ireland
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