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Tsigaridas GN, Kechriniotis AI, Tsonos CA, Delibasis KK. A Proposed Device for Controlling the Flow of Information Based on Weyl Fermions. SENSORS (BASEL, SWITZERLAND) 2024; 24:3361. [PMID: 38894152 PMCID: PMC11175101 DOI: 10.3390/s24113361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/18/2024] [Accepted: 05/21/2024] [Indexed: 06/21/2024]
Abstract
In this work we propose a novel device for controlling the flow of information using Weyl fermions. Based on a previous work by our group, we show that it is possible to fully control the flow of Weyl fermions on several different channels by applying an electric field perpendicular to the direction of motion of the particles on each channel. In this way, we can transmit information as logical bits, depending on the existence or not of a Weyl current on each channel. We also show that the response time of this device is exceptionally low, less than 1 ps, for typical values of its parameters, allowing for the control of the flow of information at extremely high rates of the order of 100 Petabits per second. Alternatively, this device could also operate as an electric field sensor. In addition, we demonstrate that Weyl fermions can be efficiently guided through the proposed device using appropriate magnetic fields. Finally, we discuss some particularly interesting remarks regarding the electromagnetic interactions of high-energy particles.
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Affiliation(s)
- Georgios N. Tsigaridas
- Department of Physics, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, GR-15772 Athens, Greece
| | | | - Christos A. Tsonos
- Department of Physics, University of Thessaly, GR-35100 Lamia, Greece; (A.I.K.); (C.A.T.)
| | - Konstantinos K. Delibasis
- Department of Computer Science and Biomedical Informatics, University of Thessaly, GR-35131 Lamia, Greece;
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2
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Rocchino L, Balduini F, Schmid H, Molinari A, Luisier M, Süß V, Felser C, Gotsmann B, Zota CB. Magnetoresistive-coupled transistor using the Weyl semimetal NbP. Nat Commun 2024; 15:710. [PMID: 38267457 PMCID: PMC11258312 DOI: 10.1038/s41467-024-44961-5] [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: 07/20/2023] [Accepted: 01/04/2024] [Indexed: 01/26/2024] Open
Abstract
Semiconductor transistors operate by modulating the charge carrier concentration of a channel material through an electric field coupled by a capacitor. This mechanism is constrained by the fundamental transport physics and material properties of such devices-attenuation of the electric field, and limited mobility and charge carrier density in semiconductor channels. In this work, we demonstrate a new type of transistor that operates through a different mechanism. The channel material is a Weyl semimetal, NbP, whose resistivity is modulated via a magnetic field generated by an integrated superconductor. Due to the exceptionally large electron mobility of this material, which reaches over 1,000,000 cm2/Vs, and the strong magnetoresistive coupling, the transistor can generate significant transconductance amplification at nanowatt levels of power. This type of device can enable new low-power amplifiers, suitable for qubit readout operation in quantum computers.
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Affiliation(s)
- Lorenzo Rocchino
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland.
| | - Federico Balduini
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Heinz Schmid
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Alan Molinari
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | | | - Vicky Süß
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187, Dresden, Germany
| | - Bernd Gotsmann
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Cezar B Zota
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
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3
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Jin G, Kim SH, Han HJ. Synthesis and Future Electronic Applications of Topological Nanomaterials. Int J Mol Sci 2023; 25:400. [PMID: 38203574 PMCID: PMC10779379 DOI: 10.3390/ijms25010400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Over the last ten years, the discovery of topological materials has opened up new areas in condensed matter physics. These materials are noted for their distinctive electronic properties, unlike conventional insulators and metals. This discovery has not only spurred new research areas but also offered innovative approaches to electronic device design. A key aspect of these materials is now that transforming them into nanostructures enhances the presence of surface or edge states, which are the key components for their unique electronic properties. In this review, we focus on recent synthesis methods, including vapor-liquid-solid (VLS) growth, chemical vapor deposition (CVD), and chemical conversion techniques. Moreover, the scaling down of topological nanomaterials has revealed new electronic and magnetic properties due to quantum confinement. This review covers their synthesis methods and the outcomes of topological nanomaterials and applications, including quantum computing, spintronics, and interconnects. Finally, we address the materials and synthesis challenges that need to be resolved prior to the practical application of topological nanomaterials in advanced electronic devices.
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Affiliation(s)
- Gangtae Jin
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA;
| | - Seo-Hyun Kim
- Department of Environment and Energy Engineering, Sungshin Women’s University, Seoul 01133, Republic of Korea;
| | - Hyeuk-Jin Han
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA;
- Department of Environment and Energy Engineering, Sungshin Women’s University, Seoul 01133, Republic of Korea;
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4
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Zivieri R, Lumetti S, Létang J. High-Mobility Topological Semimetals as Novel Materials for Huge Magnetoresistance Effect and New Type of Quantum Hall Effect. MATERIALS (BASEL, SWITZERLAND) 2023; 16:7579. [PMID: 38138720 PMCID: PMC10744697 DOI: 10.3390/ma16247579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/24/2023]
Abstract
The quantitative description of electrical and magnetotransport properties of solid-state materials has been a remarkable challenge in materials science over recent decades. Recently, the discovery of a novel class of materials-the topological semimetals-has led to a growing interest in the full understanding of their magnetotransport properties. In this review, the strong interplay among topology, band structure, and carrier mobility in recently discovered high carrier mobility topological semimetals is discussed and their effect on their magnetotransport properties is outlined. Their large magnetoresistance effect, especially in the Hall transverse configuration, and a new version of a three-dimensional quantum Hall effect observed in high-mobility Weyl and Dirac semimetals are reviewed. The possibility of designing novel quantum sensors and devices based on solid-state semimetals is also examined.
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Affiliation(s)
| | | | - Jérémy Létang
- Silicon Austria Labs, 9524 Villach, Austria; (S.L.); (J.L.)
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5
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Parfenov OE, Taldenkov AN, Averyanov DV, Sokolov IS, Kondratev OA, Borisov MM, Yakunin SN, Karateev IA, Tokmachev AM, Storchak VG. Layer-controlled evolution of electron state in the silicene intercalation compound SrSi 2. MATERIALS HORIZONS 2022; 9:2854-2862. [PMID: 36056695 DOI: 10.1039/d2mh00640e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Silicene, a Si-based analogue of graphene, holds a high promise for electronics because of its exceptional properties but a high chemical reactivity makes it a very challenging material to work with. The silicene lattice can be stabilized by active metals to form stoichiometric compounds MSi2. Being candidate topological semimetals, these materials provide an opportunity to probe layer dependence of unconventional electronic structures. It is demonstrated here that in the silicene compound SrSi2, the number of monolayers controls the electronic state. A series of films ranging from bulk-like multilayers down to a single monolayer have been synthesized on silicon and characterized with a combination of techniques - from electron and X-ray diffraction to high-resolution electron microscopy. Transport measurements reveal evolution of the chiral anomaly in bulk SrSi2 to weak localization in ultrathin films down to 3 monolayers followed by 3D and 2D strong localization in 2 and 1 monolayers, respectively. The results outline the range of stability of the chiral state, important for practical applications, and shed light on the localization phenomena in the limit of a few monolayers.
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Affiliation(s)
- Oleg E Parfenov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Dmitry V Averyanov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Ivan S Sokolov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Oleg A Kondratev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Mikhail M Borisov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Sergey N Yakunin
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Igor A Karateev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, Moscow 123182, Russia.
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6
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Tilmann B, Pandeya AK, Grinblat G, Menezes LDS, Li Y, Shekhar C, Felser C, Parkin SSP, Bedoya-Pinto A, Maier SA. Ultrafast Sub-100 fs All-Optical Modulation and Efficient Third-Harmonic Generation in Weyl Semimetal Niobium Phosphide Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106733. [PMID: 35172033 DOI: 10.1002/adma.202106733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 02/11/2022] [Indexed: 06/14/2023]
Abstract
Since their experimental discovery in 2015, Weyl semimetals have generated a large amount of attention due their intriguing physical properties that arise from their linear electron dispersion relation and topological surface states. In particular, in the field of nonlinear (NL) optics and light harvesting, Weyl semimetals have shown outstanding performances and achieved record NL conversion coefficients. In this context, the first steps toward Weyl semimetal nanophotonics are performed here by thoroughly characterizing the linear and NL optical behavior of epitaxially grown niobium phosphide (NbP) thin films, covering the visible to the near-infrared regime of the electromagnetic spectrum. Despite the measured high linear absorption, third-harmonic generation studies demonstrate high conversion efficiencies up to 10-4 % that can be attributed to the topological electron states at the surface of the material. Furthermore, nondegenerate pump-probe measurements with sub-10 fs pulses reveal a maximum modulation depth of ≈1%, completely decaying within 100 fs and therefore suggesting the possibility of developing all-optical switching devices based on NbP. Altogether, this work reveals the promising NL optical properties of Weyl semimetal thin films, which outperform bulk crystals of the same material, laying the grounds for nanoscale applications, enabled by top-down nanostructuring, such as light-harvesting, on-chip frequency conversion, and all-optical processing.
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Affiliation(s)
- Benjamin Tilmann
- Chair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität München, 80539, München, Germany
| | | | - Gustavo Grinblat
- Departamento de Física, FCEN, IFIBA-CONICET, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
| | - Leonardo de S Menezes
- Chair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität München, 80539, München, Germany
- Departmento de Física, Universidade Federal de Pernambuco, Recife-PE, 50670-901, Brazil
| | - Yi Li
- School of Microelectronics, MOE Engineering Research Center of Integrated Circuits for Next Generation Communications, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Chandra Shekhar
- Max Planck-Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck-Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck-Institute of Microstructure Physics, Halle, 06120, Saale, Germany
| | | | - Stefan A Maier
- Chair in Hybrid Nanosystems, Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität München, 80539, München, Germany
- The Blackett Laboratory, Department of Physics, Imperial College London, London, SW7 2AZ, UK
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7
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Preparation of NbAs Single Crystal by the Seed Growth Process. CRYSTALS 2022. [DOI: 10.3390/cryst12020249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A Weyl semimetal is a novel crystal with low-energy electronic excitations that behave as Weyl fermions. It has received worldwide interest and was believed to have introduced the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, it is not easy to obtain a single large-sized crystal because there are many nucleations in the preparation process. A bottom-seed CVT growth method is proposed in this paper, and we acquired the large-sized, high-quality NbAs single crystals up to 4 × 3 × 3 mm3 finally. X-ray diffraction and STEM confirmed that they are tetragonal NbAs, which the key is to using the seed crystal in a vertical growth furnace. Notably, the photoelectric properties of the crystal are obtained under the existing conditions, which paves the way for follow-up work.
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8
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Tiwari RP, Birajdar B, Ghosh RK. Intrinsic ferroelectricity and large bulk photovoltaic effect in novel two-dimensional buckled honeycomb-like lattice of NbP: first-principles study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:385302. [PMID: 34229302 DOI: 10.1088/1361-648x/ac117f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
Using first-principles calculations, we predict that the two-dimensional (2D) monolayers of NbP with the buckled honeycomb-like and puckered tetragonal structure can be obtained from the (110) and (001) orientations, respectively, of its bulk crystal structure. The electronic properties of these monolayers are spectacularly different as tetragonal lattice is metallic whereas the honeycomb-like lattice (h-NbP) is a semiconductor and exhibits intrinsic ferroelectricity originating from a raresd2-sp2hybridization. The shift current bulk photovoltaic effect (BPVE) is systematically investigated in the h-NbP monolayer (1.21 Å thickness) using the Wannier interpolation method. Strong absorption of visible light at ∼2 eV and a large 3D shift current of ∼180μA V-2is obtained which is attributed to the partial delocalization of Bloch states due tosd2-sp2hybridization. We compare the shift current response of h-NbP monolayer with that of some previously reported bulk ferroelectrics and 2D monolayers, suggesting that h-NbP monolayer can yield a large shift current at an ultimate thickness and is a promising 2D material for the BPVE application under the visible light. Strain effect is also investigated, revealing that the h-NbP monolayer is dynamically stable up to a strain limit of ±3%, and the shift current increases by ∼9% at a compressive strain of -3% as the Bloch states are more delocalized due to the strengthening ofsd2-sp2hybridization. The results presented in this study can pave the paths to fabricate the 2D monolayered structures of NbP, and realize the BPVE based next-generation solar cells of h-NbP monolayer.
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Affiliation(s)
- Rajender Prasad Tiwari
- Special Center for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067, India
- Asia Pacific Center for Theoretical Physics, Pohang, 37673, Republic of Korea
| | - Balaji Birajdar
- Special Center for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ram Krishna Ghosh
- Special Center for Nano Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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9
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Bedoya-Pinto A, Liu D, Tan H, Pandeya AK, Chang K, Zhang J, Parkin SSP. Large Fermi-Energy Shift and Suppression of Trivial Surface States in NbP Weyl Semimetal Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008634. [PMID: 33942944 DOI: 10.1002/adma.202008634] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/21/2021] [Indexed: 06/12/2023]
Abstract
Weyl semimetals, a class of 3D topological materials, exhibit a unique electronic structure featuring linear band crossings and disjoint surface states (Fermi-arcs). While first demonstrations of topologically driven phenomena have been realized in bulk crystals, efficient routes to control the electronic structure have remained largely unexplored. Here, a dramatic modification of the electronic structure in epitaxially grown NbP Weyl semimetal thin films is reported, using in situ surface engineering and chemical doping strategies that do not alter the NbP lattice structure and symmetry, retaining its topological nature. Through the preparation of a dangling-bond-free, P-terminated surface which manifests in a surface reconstruction, all the well-known trivial surface states of NbP are fully suppressed, resulting in a purely topological Fermi-arc dispersion. In addition, a substantial Fermi-energy shift from -0.2 to 0.3 eV across the Weyl points is achieved by surface chemical doping, unlocking access to the hitherto unexplored n-type region of the Weyl spectrum. These findings constitute a milestone toward surface-state and Fermi-level engineering of topological bands in Weyl semimetals, and, while there are still challenges in minimizing doping-driven disorder and grain boundary density in the films, they do represent a major advance to realize device heterostructures based on Weyl physics.
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Affiliation(s)
- Amilcar Bedoya-Pinto
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Defa Liu
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Hengxin Tan
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | | | - Kai Chang
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Jibo Zhang
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
| | - Stuart S P Parkin
- Max Planck-Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany
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10
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Li SH, Qi MY, Tang ZR, Xu YJ. Nanostructured metal phosphides: from controllable synthesis to sustainable catalysis. Chem Soc Rev 2021; 50:7539-7586. [PMID: 34002737 DOI: 10.1039/d1cs00323b] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Metal phosphides (MPs) with unique and desirable physicochemical properties provide promising potential in practical applications, such as the catalysis, gas/humidity sensor, environmental remediation, and energy storage fields, especially for transition metal phosphides (TMPs) and MPs consisting of group IIIA and IVA metal elements. Most studies, however, on the synthesis of MP nanomaterials still face intractable challenges, encompassing the need for a more thorough understanding of the growth mechanism, strategies for large-scale synthesis of targeted high-quality MPs, and practical achievement of functional applications. This review aims at providing a comprehensive update on the controllable synthetic strategies for MPs from various metal sources. Additionally, different passivation strategies for engineering the structural and electronic properties of MP nanostructures are scrutinized. Then, we showcase the implementable applications of MP-based materials in emerging sustainable catalytic fields including electrocatalysis, photocatalysis, mild thermocatalysis, and related hybrid systems. Finally, we offer a rational perspective on future opportunities and remaining challenges for the development of MPs in the materials science and sustainable catalysis fields.
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Affiliation(s)
- Shao-Hai Li
- College of Chemistry, State Key Laboratory of Photocatalysis on Energy and Environment, New Campus, Fuzhou University, Fuzhou, 350116, P. R. China.
| | - Ming-Yu Qi
- College of Chemistry, State Key Laboratory of Photocatalysis on Energy and Environment, New Campus, Fuzhou University, Fuzhou, 350116, P. R. China.
| | - Zi-Rong Tang
- College of Chemistry, State Key Laboratory of Photocatalysis on Energy and Environment, New Campus, Fuzhou University, Fuzhou, 350116, P. R. China.
| | - Yi-Jun Xu
- College of Chemistry, State Key Laboratory of Photocatalysis on Energy and Environment, New Campus, Fuzhou University, Fuzhou, 350116, P. R. China.
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11
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Jin C, Olsen BC, Luber EJ, Buriak JM. van der Waals Epitaxy of Soft Twisted Bilayers: Lattice Relaxation and Mass Density Waves. ACS NANO 2020; 14:13441-13450. [PMID: 32931263 DOI: 10.1021/acsnano.0c05310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Interfaces comprising incommensurate or twisted hexagonal lattices are ubiquitous and of great interest, from adsorbed organic/inorganic interfaces in electronic devices, to superlubricants, and more recently to van der Waals bilayer heterostructures (vdWHs) of graphene and other 2D materials that demonstrate a range of properties such as superconductivity and ferromagnetism. Here we show how growth of 2D crystalline domains of soft block copolymers (BCPs) on patterned hard hexagonal lattices provide fundamental insights into van der Waals heteroepitaxy. At moderate registration forces, it is experimentally found that these BCP-hard lattice vdWHs do not adopt a simple moiré superstructure, but instead adopt local structural relaxations known as mass density waves (MDWs). Simulations reveal that MDWs are a primary mechanism of energy minimization and are the origin of the observed preferential twist angle between the lattices.
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Affiliation(s)
- Cong Jin
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Brian C Olsen
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Erik J Luber
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Jillian M Buriak
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
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12
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Li Y, Xia J. Cubic Hafnium Nitride: A Novel Topological Semimetal Hosting a 0-Dimensional (0-D) Nodal Point and a 1-D Topological Nodal Ring. Front Chem 2020; 8:727. [PMID: 33005603 PMCID: PMC7479206 DOI: 10.3389/fchem.2020.00727] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 07/14/2020] [Indexed: 11/13/2022] Open
Abstract
Very recently, topological semimetals with nontrivial band crossing and associated topological surface states have received widespread attention. Various types of topological semimetals, including nodal point semimetals, nodal line semimetals, and nodal surface semimetals, have been predicted from first principles. In absence of spin-orbit coupling (SOC) effect, we propose that cubic-type hafnium nitride (HfN) with a P m 3 ¯ m space group is a novel topological semimetal hosting a rare 0-D triple nodal point and a 1-D topological nodal ring. More importantly, the interesting 0-D and 1-D topological states all occur near the Fermi level, and these topological states are not disturbed by other extraneous bands. When the SOC effect is taken into consideration, 0-D triple nodal point was gapped and a new 0-D topological element, namely, Dirac point appears along Γ-R path. Finally, the dynamical and mechanical stabilities of this semimetal and its associated mechanical properties are discussed in order to provide a reference for future investigations. Our work promises that HfN can serve as a superior topological semimetal with high stability, excellent mechanical properties, and rich topological states.
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Affiliation(s)
- Yang Li
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing, China
- Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming, China
| | - Jihong Xia
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing, China
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13
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Bedoya-Pinto A, Pandeya AK, Liu D, Deniz H, Chang K, Tan H, Han H, Jena J, Kostanovskiy I, Parkin SSP. Realization of Epitaxial NbP and TaP Weyl Semimetal Thin Films. ACS NANO 2020; 14:4405-4413. [PMID: 32053338 PMCID: PMC7307967 DOI: 10.1021/acsnano.9b09997] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/13/2020] [Indexed: 06/10/2023]
Abstract
Weyl semimetals (WSMs) exhibit an electronic structure governed by linear band dispersions and degenerate (Weyl) points that lead to exotic physical phenomena. While WSMs were established in bulk monopnictide compounds several years ago, the growth of thin films remains a challenge. Here, we report the bottom-up synthesis of single-crystalline NbP and TaP thin films, 9 to 70 nm thick, by means of molecular beam epitaxy. The as-grown epitaxial films feature a phosphorus-rich stoichiometry, a tensile-strained unit cell, and a homogeneous surface termination, unlike their bulk crystal counterparts. These properties result in an electronic structure governed by topological surface states as directly observed using in situ momentum photoemission microscopy, along with a Fermi-level shift of -0.2 eV with respect to the intrinsic chemical potential. Although the Fermi energy of the as-grown samples is still far from the Weyl points, carrier mobilities close to 103 cm2/(V s) have been measured at room temperature in patterned Hall-bar devices. The ability to grow thin films of Weyl semimetals that can be tailored by doping or strain, is an important step toward the fabrication of functional WSM-based devices and heterostructures.
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Affiliation(s)
- Amilcar Bedoya-Pinto
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | | | - Defa Liu
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hakan Deniz
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Kai Chang
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hengxin Tan
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Hyeon Han
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Jagannath Jena
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Ilya Kostanovskiy
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
| | - Stuart S. P. Parkin
- Max Planck-Institute of Microstructure
Physics, Weinberg 2, 06120 Halle (Saale), Germany
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