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S A, Amaladass EP, Amirthapandian S, David C, Mani A. The effect of charged particle irradiation on the transport properties of bismuth chalcogenide topological insulators: a brief review. Phys Chem Chem Phys 2024; 26:2745-2767. [PMID: 38179833 DOI: 10.1039/d3cp02462h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
Topological insulators (TIs) offer a novel platform for achieving exciting applications, such as low-power electronics, spintronics, and quantum computation. Hence, the spin-momentum locked and topologically nontrivial surface state of TIs is highly coveted by the research and development industry. Particle irradiation in TIs is a fast-growing field of research owing to the industrial scalability of the particle irradiation technique. Unfortunately, real three-dimensional TI materials, such as bismuth selenide, invariably host a significant population of charged native defects, which cause the ideally insulating bulk to behave like a metal, masking the relatively weak signatures of metallic topological surface states. Particle irradiation has emerged as an effective technique for Fermi energy tuning to achieve an insulating bulk in TI along with other popularly practiced methods, such as substitution doping and electrical gating. Irradiation methods have been used for many years to enhance the thermoelectric properties of bismuth chalcogenides, predominantly by increasing carrier density. In contrast, uncovering the surface states in bismuth-based TI requires the suppression of carrier density via particle irradiation. Hence, the literature on the effect of irradiation on bismuth chalcogenides extends widely to both ends of the spectrum (thermoelectric and topological properties). This review attempts to collate the available literature on particle irradiation-driven Fermi energy tuning and the modification of topological surface states in TI. Recent studies on particle irradiation in TI have focused on precise local modifications in the TI system to induce magnetic topological ordering and surface selective topological superconductivity. Promising proposals for TI-integrated circuits have also been put forth. The eclectic range of irradiation-based studies on TI has been reviewed in this manuscript.
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Affiliation(s)
- Abhirami S
- Materials Science Group, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India.
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai-400094, India
| | - E P Amaladass
- Materials Science Group, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India.
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai-400094, India
| | - S Amirthapandian
- Materials Science Group, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India.
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai-400094, India
| | - C David
- Materials Science Group, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India.
| | - Awadhesh Mani
- Materials Science Group, Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India.
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai-400094, India
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Nilforoushan N, Casula M, Amaricci A, Caputo M, Caillaux J, Khalil L, Papalazarou E, Simon P, Perfetti L, Vobornik I, Das PK, Fujii J, Barinov A, Santos-Cottin D, Klein Y, Fabrizio M, Gauzzi A, Marsi M. Moving Dirac nodes by chemical substitution. Proc Natl Acad Sci U S A 2021; 118:e2108617118. [PMID: 34385327 DOI: 10.1073/pnas.2108617118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dirac fermions play a central role in the study of topological phases, for they can generate a variety of exotic states, such as Weyl semimetals and topological insulators. The control and manipulation of Dirac fermions constitute a fundamental step toward the realization of novel concepts of electronic devices and quantum computation. By means of Angle-Resolved Photo-Emission Spectroscopy (ARPES) experiments and ab initio simulations, here, we show that Dirac states can be effectively tuned by doping a transition metal sulfide, [Formula: see text], through Co/Ni substitution. The symmetry and chemical characteristics of this material, combined with the modification of the charge-transfer gap of [Formula: see text] across its phase diagram, lead to the formation of Dirac lines, whose position in k-space can be displaced along the [Formula: see text] symmetry direction and their form reshaped. Not only does the doping x tailor the location and shape of the Dirac bands, but it also controls the metal-insulator transition in the same compound, making [Formula: see text] a model system to functionalize Dirac materials by varying the strength of electron correlations.
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Schönhense G, Babenkov S, Vasilyev D, Elmers HJ, Medjanik K. Single-hemisphere photoelectron momentum microscope with time-of-flight recording. Rev Sci Instrum 2020; 91:123110. [PMID: 33379996 DOI: 10.1063/5.0024074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 11/26/2020] [Indexed: 06/12/2023]
Abstract
Photoelectron momentum microscopy is an emerging powerful method for angle-resolved photoelectron spectroscopy (ARPES), especially in combination with imaging spin filters. These instruments record kx-ky images, typically exceeding a full Brillouin zone. As energy filters, double-hemispherical or time-of-flight (ToF) devices are in use. Here, we present a new approach for momentum mapping of the full half-space, based on a large single hemispherical analyzer (path radius of 225 mm). Excitation by an unfocused He lamp yielded an energy resolution of 7.7 meV. The performance is demonstrated by k-imaging of quantum-well states in Au and Xe multilayers. The α2-aberration term (α, entrance angle in the dispersive plane) and the transit-time spread of the electrons in the spherical field are studied in a large pass-energy (6 eV-660 eV) and angular range (α up to ±7°). It is discussed how the method circumvents the preconditions of previous theoretical work on the resolution limitation due to the α2-term and the transit-time spread, being detrimental for time-resolved experiments. Thanks to k-resolved detection, both effects can be corrected numerically. We introduce a dispersive-plus-ToF hybrid mode of operation, with an imaging ToF analyzer behind the exit slit of the hemisphere. This instrument captures 3D data arrays I (EB, kx, ky), yielding a gain up to N2 in recording efficiency (N being the number of resolved time slices). A key application will be ARPES at sources with high pulse rates such as synchrotrons with 500 MHz time structure.
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Affiliation(s)
- G Schönhense
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - S Babenkov
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - D Vasilyev
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - H-J Elmers
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
| | - K Medjanik
- Johannes Gutenberg-Universität, Institut für Physik, 55128 Mainz, Germany
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Holtgrewe K, Mahatha SK, Sheverdyaeva PM, Moras P, Flammini R, Colonna S, Ronci F, Papagno M, Barla A, Petaccia L, Aliev ZS, Babanly MB, Chulkov EV, Sanna S, Hogan C, Carbone C. Topologization of β-antimonene on Bi 2Se 3 via proximity effects. Sci Rep 2020; 10:14619. [PMID: 32884112 PMCID: PMC7471962 DOI: 10.1038/s41598-020-71624-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 08/19/2020] [Indexed: 11/09/2022] Open
Abstract
Topological surface states usually emerge at the boundary between a topological and a conventional insulator. Their precise physical character and spatial localization depend on the complex interplay between the chemical, structural and electronic properties of the two insulators in contact. Using a lattice-matched heterointerface of single and double bilayers of β-antimonene and bismuth selenide, we perform a comprehensive experimental and theoretical study of the chiral surface states by means of microscopy and spectroscopic measurements complemented by first-principles calculations. We demonstrate that, although β-antimonene is a trivial insulator in its free-standing form, it inherits the unique symmetry-protected spin texture from the substrate via a proximity effect that induces outward migration of the topological state. This "topologization" of β-antimonene is found to be driven by the hybridization of the bands from either side of the interface.
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Affiliation(s)
- K Holtgrewe
- Institut für Theoretische Physik and Center for Materials Research (LaMa), Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, 35392, Gießen, Germany
| | - S K Mahatha
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, 34149, Trieste, Italy.
- Ruprecht Haensel Laboratory, Deutsches Elektronen-Synchrotron DESY, 22607, Hamburg, Germany.
| | - P M Sheverdyaeva
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, 34149, Trieste, Italy
| | - P Moras
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, 34149, Trieste, Italy
| | - R Flammini
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, Via del Fosso del Cavaliere 100, 00133, Roma, Italy
| | - S Colonna
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, Via del Fosso del Cavaliere 100, 00133, Roma, Italy
| | - F Ronci
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, Via del Fosso del Cavaliere 100, 00133, Roma, Italy
| | - M Papagno
- Dipartimento di Fisica, CS, Università Della Calabria, Via P. Bucci, 87036, Arcavacata di Rende, Italy
| | - A Barla
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, 34149, Trieste, Italy
| | - L Petaccia
- Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, 34149, Trieste, Italy
| | - Z S Aliev
- Azerbaijan State Oil and Industry University, AZ1010, Baku, Azerbaijan
| | - M B Babanly
- Institute Catalysis and Inorganic Chemistry, Azerbaijan National Academy of Science, AZ1143, Baku, Azerbaijan
| | - E V Chulkov
- Departamento de Fisica de Materiales, UPV/EHU, 20080, Donostia-San Sebastian, Basque Country, Spain
- Donostia International Physics Center (DIPC), P. de Manuel Lardizabal 4, 20018, San Sebastián, Basque Country, Spain
- Saint Petersburg State University, 198504, Saint Petersburg, Russia
- Institute of Strength Physics and Materials Science, Russian Academy of Sciences, 634021, Tomsk, Russia
| | - S Sanna
- Institut für Theoretische Physik and Center for Materials Research (LaMa), Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, 35392, Gießen, Germany
| | - C Hogan
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, Via del Fosso del Cavaliere 100, 00133, Roma, Italy
| | - C Carbone
- Istituto di Struttura Della Materia, Consiglio Nazionale Delle Ricerche, 34149, Trieste, Italy
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Tamtögl A, Sacchi M, Avidor N, Calvo-Almazán I, Townsend PSM, Bremholm M, Hofmann P, Ellis J, Allison W. Nanoscopic diffusion of water on a topological insulator. Nat Commun 2020; 11:278. [PMID: 31937778 PMCID: PMC6959239 DOI: 10.1038/s41467-019-14064-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 12/13/2019] [Indexed: 11/12/2022] Open
Abstract
The microscopic motion of water is a central question, but gaining experimental information about the interfacial dynamics of water in fields such as catalysis, biophysics and nanotribology is challenging due to its ultrafast motion, and the complex interplay of inter-molecular and molecule-surface interactions. Here we present an experimental and computational study of the nanoscale-nanosecond motion of water at the surface of a topological insulator (TI), Bi[Formula: see text]Te[Formula: see text]. Understanding the chemistry and motion of molecules on TI surfaces, while considered a key to design and manufacturing for future applications, has hitherto been hardly addressed experimentally. By combining helium spin-echo spectroscopy and density functional theory calculations, we are able to obtain a general insight into the diffusion of water on Bi[Formula: see text]Te[Formula: see text]. Instead of Brownian motion, we find an activated jump diffusion mechanism. Signatures of correlated motion suggest unusual repulsive interactions between the water molecules. From the lineshape broadening we determine the diffusion coefficient, the diffusion energy and the pre-exponential factor.
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Affiliation(s)
- Anton Tamtögl
- Institute of Experimental Physics, Graz University of Technology, 8010, Graz, Austria.
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK.
| | - Marco Sacchi
- Department of Chemistry, University of Surrey, Guildford, GU2 7XH, UK
| | - Nadav Avidor
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK
| | - Irene Calvo-Almazán
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK
- Material Science Division, Argonne National Laboratory, Argonne, 60439, IL, USA
| | - Peter S M Townsend
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK
- Department of Chemistry and Chemical Biology, Rutgers University, 123 Bevier Road, Piscataway, NJ, 08854, USA
| | - Martin Bremholm
- Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, 8000, Aarhus, Denmark
| | - Philip Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000, Aarhus C, Denmark
| | - John Ellis
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK
| | - William Allison
- Cavendish Laboratory, J. J. Thompson Avenue, Cambridge, CB3 0HE, UK
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Polyakov A, Mohseni K, Castro GR, Rubio-Zuazo J, Zeugner A, Isaeva A, Chen YJ, Tusche C, Meyerheim HL. A bismuth triiodide monosheet on Bi 2Se 3(0001). Sci Rep 2019; 9:4052. [PMID: 30858434 PMCID: PMC6411853 DOI: 10.1038/s41598-019-40506-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/18/2019] [Indexed: 12/02/2022] Open
Abstract
A stable BiI3 monosheet has been grown for the first time on the (0001) surface of the topological insulator Bi2Se3 as confirmed by scanning tunnelling microscopy, surface X-ray diffraction, and X-ray photoemision spectroscopy. BiI3 is deposited by molecular beam epitaxy from the crystalline BiTeI precursor that undergoes decomposition sublimation. The key fragment of the bulk BiI3 structure, \documentclass[12pt]{minimal}
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\begin{document}$${{\rm{a}}}_{\infty }^{2}$$\end{document}a∞2[I—Bi—I] layer of edge-sharing BiI6 octahedra, is preserved in the ultra-thin film limit, but exhibits large atomic relaxations. The stacking sequence of the trilayers and alternations of the Bi—I distances in the monosheet are the same as in the bulk BiI3 structure. Momentum resolved photoemission spectroscopy indicates a direct band gap of 1.2 eV. The Dirac surface state is completely destroyed and a new flat band appears in the band gap of the BiI3 film that could be interpreted as an interface state.
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Affiliation(s)
- Andrey Polyakov
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Katayoon Mohseni
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany
| | - German R Castro
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France.,Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), 28049, Madrid, Spain
| | - Juan Rubio-Zuazo
- SpLine, Spanish CRG BM25 Beamline at the ESRF (The European Synchrotron), F-38000, Grenoble, France.,Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), 28049, Madrid, Spain
| | - Alexander Zeugner
- Department of Chemistry and Food Chemistry, TU Dresden, Helmholtzstraße 10, 01069, Dresden, Germany
| | - Anna Isaeva
- Technische Universität Dresden, Institut für Festkörper- und Materialphysik, Helmholtzstraße 10, 01069, Dresden, Germany.,Leibniz-Institut für Festkörper-und Werkstoffforschung Dresden, Helmholtzstraße 20, 01069, Dresden, Germany
| | - Ying-Jiun Chen
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Christian Tusche
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.,Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Holger L Meyerheim
- Max-Planck-Institut für Mikrostukturphysik, Weinberg 2, 06120, Halle, Germany.
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Pia AD, Lisi S, Luca OD, Warr DA, Lawrence J, Otrokov MM, Aliev ZS, Chulkov EV, Agostino RG, Arnau A, Papagno M, Costantini G. TCNQ Physisorption on the Topological Insulator Bi 2 Se 3. Chemphyschem 2018; 19:2405-2410. [PMID: 29847012 DOI: 10.1002/cphc.201800259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Indexed: 11/07/2022]
Abstract
Topological insulators are promising candidates for spintronic applications due to their topologically protected, spin-momentum locked and gapless surface states. The breaking of the time-reversal symmetry after the introduction of magnetic impurities, such as 3d transition metal atoms embedded in two-dimensional molecular networks, could lead to several phenomena interesting for device fabrication. The first step towards the fabrication of metal-organic coordination networks on the surface of a topological insulator is to investigate the adsorption of the pure molecular layer, which is the aim of this study. Here, the effect of the deposition of the electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules on the surface of a prototypical topological insulator, bismuth selenide (Bi2 Se3 ), is investigated. Scanning tunneling microscope images at low-temperature reveal the formation of a highly ordered two-dimensional molecular network. The essentially unperturbed electronic structure of the topological insulator observed by photoemission spectroscopy measurements demonstrates a negligible charge transfer between the molecular layer and the substrate. Density functional theory calculations confirm the picture of a weakly interacting adsorbed molecular layer. These results reveal significant potential of TCNQ for the realization of metal-organic coordination networks on the topological insulator surface.
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Affiliation(s)
- Ada Della Pia
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Simone Lisi
- Institut Néel, 25 Rue des Martyrs BP 166, 38042, Grenoble, France
| | - Oreste De Luca
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Daniel A Warr
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - J Lawrence
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Mikhail M Otrokov
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Saint Petersburg State University, 198504, Saint Petersburg, Russia
- Tomsk State University, 634050, Tomsk, Russia
| | - Ziya S Aliev
- Azerbaijan State Oil and Industry University, AZ1010, Baku, Azerbaijan
- Materials Science and Nanotechnology Department, Near East University, North Cyprus, Mersin 10, 99138, Nicosia, Turkey
| | - Evgueni V Chulkov
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Saint Petersburg State University, 198504, Saint Petersburg, Russia
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Raffaele G Agostino
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Andrés Arnau
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Marco Papagno
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Giovanni Costantini
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
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Abstract
2D topological insulators exhibit insulating bulk and conducting edge states with a Dirac point, which at times is within the energy gap and could be on either side of the Fermi energy. In this study, we demonstrate a method to tune the energy of the Dirac edge state by introducing halides as dopants in Bi2Se3. We chose halides to substitute the anion, so that due to higher atomic number (of iodine, for example) with respect to selenium, the spin-orbit coupling parameter could be enhanced, leading to the significant separation of the Dirac point from the Fermi energy. With different halogens having different atomic numbers on either side of selenium, the Dirac point could hence be tuned towards both directions. The dopants, due to their heterovalent nature with respect to selenide, introduce carriers in the lattice and consequently, also shift the Fermi energy. We show that the Dirac point with respect to Fermi energy could be correlated to the dopant's atomic number and thus the atomic-number-induced spin-orbit coupling parameter. Strains developed in the lattice due to a mismatch in the effective ionic radii of the dopants and the host anion affected distribution of band energies, leaving the (distribution of) Dirac point unaffected due to its topologically protected nature.
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Affiliation(s)
- Salma Khatun
- Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
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Causer GL, Cortie DL, Zhu H, Ionescu M, Mankey GJ, Wang XL, Klose F. Direct Measurement of the Intrinsic Sharpness of Magnetic Interfaces Formed by Chemical Disorder Using a He + Beam. ACS Appl Mater Interfaces 2018; 10:16216-16224. [PMID: 29701447 DOI: 10.1021/acsami.8b03197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Using ion beams to locally modify material properties and subsequently drive magnetic phase transitions is rapidly gaining momentum as the technique of choice for the fabrication of magnetic nanoelements. This is because the method provides the capability to engineer in three dimensions on the nanometer length scale. This will be an important consideration for several emerging magnetic technologies (e.g., spintronic devices and racetrack and random-access memories) where device functionality will hinge on the spatial definition of the incorporated magnetic nanoelements. In this work, the fundamental sharpness of a magnetic interface formed by nanomachining FePt3 films using He+ irradiation is investigated. Through careful selection of the irradiating ion energy and fluence, room-temperature ferromagnetism is locally induced into a fractional volume of a paramagnetic (PM) FePt3 film by modifying the chemical order parameter. A combination of transmission electron microscopy, magnetometry, and polarized neutron reflectometry measurements demonstrates that the interface over which the PM-to-ferromagnetic modulation occurs in this model system is confined to a few atomic monolayers only, while the structural boundary transition is less well-defined. Using complementary density functional theory, the mechanism for the ion-beam-induced magnetic transition is elucidated and shown to be caused by an intermixing of Fe and Pt atoms in antisite defects above a threshold density.
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Affiliation(s)
- Grace L Causer
- Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong , New South Wales 2500 , Australia
- Australian Nuclear Science and Technology Organisation , Lucas Heights , New South Wales 2234 , Australia
| | - David L Cortie
- Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong , New South Wales 2500 , Australia
| | - Hanliang Zhu
- Australian Nuclear Science and Technology Organisation , Lucas Heights , New South Wales 2234 , Australia
| | - Mihail Ionescu
- Australian Nuclear Science and Technology Organisation , Lucas Heights , New South Wales 2234 , Australia
| | - Gary J Mankey
- Department of Physics and Astronomy , University of Alabama , Tuscaloosa , Alabama 35487 , United States
| | - Xiaolin L Wang
- Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong , New South Wales 2500 , Australia
| | - Frank Klose
- Australian Nuclear Science and Technology Organisation , Lucas Heights , New South Wales 2234 , Australia
- Guangdong Technion-Israel Institute of Technology , Shantou 515063 , P. R. China
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10
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Babanly MB, Chulkov EV, Aliev ZS, Shevelkov AV, Amiraslanov IR. Phase diagrams in materials science of topological insulators based on metal chalcogenides. RUSS J INORG CHEM+ 2017. [DOI: 10.1134/s0036023617130034] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Banerjee A, Rai A, Majhi K, Barman SR, Ganesan R, Anil Kumar PS. Intermediate stages of surface state formation and collapse of topological protection to transport in Bi 2Se 3. J Phys Condens Matter 2017; 29:185001. [PMID: 28350542 DOI: 10.1088/1361-648x/aa666a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Surface states consisting of helical Dirac fermions have been extensively studied in three-dimensional topological insulators. Yet, experiments to date have only investigated fully formed topological surface states (TSS) and it is not known whether preformed or partially formed surface states can exist or what properties they could potentially host. Here, by decorating thin films of Bi2Se3 with nanosized islands of the same material, we show for the first time that not only can surface states exist in various intermediate stages of formation but they exhibit unique properties not accessible in fully formed TSS. These include tunability of the Dirac cone mass, vertical migration of the surface state wave-function and the appearance of mid-gap Rashba-like states as exemplified by our theoretical model for decorated TIs. Our experiments show that an interplay of Rashba and Dirac fermions on the surface leads to an intriguing multi-channel weak anti-localization effect concomitant with an unprecedented tuning of the topological protection to transport. Our work offers a new route to engineer topological surface states involving Dirac-Rashba coupling by nano-scale decoration of TI thin films, at the same time shedding light on the real-space mechanism of surface state formation in general.
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Affiliation(s)
- Abhishek Banerjee
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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Munoz F, Vergniory MG, Rauch T, Henk J, Chulkov EV, Mertig I, Botti S, Marques MAL, Romero AH. Topological Crystalline Insulator in a New Bi Semiconducting Phase. Sci Rep 2016; 6:21790. [PMID: 26905601 PMCID: PMC4764853 DOI: 10.1038/srep21790] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/01/2016] [Indexed: 11/20/2022] Open
Abstract
Topological crystalline insulators are a type of topological insulators whose topological surface states are protected by a crystal symmetry, thus the surface gap can be tuned by applying strain or an electric field. In this paper we predict by means of ab initio calculations a new phase of Bi which is a topological crystalline insulator characterized by a mirror Chern number nM = −2, but not a strong topological insulator. This system presents an exceptional property: at the (001) surface its Dirac cones are pinned at the surface high-symmetry points. As a consequence they are also protected by time-reversal symmetry and can survive against weak disorder even if in-plane mirror symmetry is broken at the surface. Taking advantage of this dual protection, we present a strategy to tune the band-gap based on a topological phase transition unique to this system. Since the spin-texture of these topological surface states reduces the back-scattering in carrier transport, this effective band-engineering is expected to be suitable for electronic and optoelectronic devices with reduced dissipation.
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Affiliation(s)
- F Munoz
- Departamento de Física, Facultad de Ciencias, Universidad de Chile &Centro para el Desarrollo de la Nanociencia y la Nanotecnologia, CEDENNA, Santiago, Chile
| | - M G Vergniory
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
| | - T Rauch
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany
| | - J Henk
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany
| | - E V Chulkov
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain.,Tomsk State University, Tomsk, Russia.,Departamento de Fisica de materiales, Facultad de Ciencias Quimicas, UPV/EHU and Centro de Fisica de Materiales, Centro Mixto CSIC-UPV/EHU, San Sebastian, Spain.,St. Petersburg State University, St. Petersburg, Russia
| | - I Mertig
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany.,Max Planck Institute of Microstructure Physics, Halle, Germany
| | - S Botti
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Jena, Germany.,Institut Lumière Matière (UMR5306), Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex, France
| | - M A L Marques
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany.,Institut Lumière Matière (UMR5306), Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex, France
| | - A H Romero
- Physics Department, West Virginia University, Morgantown, USA
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