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Cysne TP, Costa M, Canonico LM, Nardelli MB, Muniz RB, Rappoport TG. Cysne et al. Reply. Phys Rev Lett 2021; 127:149702. [PMID: 34652177 DOI: 10.1103/physrevlett.127.149702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Tarik P Cysne
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói RJ, Brazil
| | - Marcio Costa
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói RJ, Brazil
| | - Luis M Canonico
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - M Buongiorno Nardelli
- Department of Physics and Department of Chemistry, University of North Texas, Denton, Texas 76203, USA
| | - R B Muniz
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói RJ, Brazil
| | - Tatiana G Rappoport
- Instituto de Telecomunicações, Instituto Superior Tecnico, University of Lisbon, Avenida Rovisco Pais 1, Lisboa 1049001, Portugal
- Instituto de Física, Universidade Federal do Rio de Janeiro, C.P. 68528, 21941-972 Rio de Janeiro RJ, Brazil
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Cysne TP, Costa M, Canonico LM, Nardelli MB, Muniz RB, Rappoport TG. Disentangling Orbital and Valley Hall Effects in Bilayers of Transition Metal Dichalcogenides. Phys Rev Lett 2021; 126:056601. [PMID: 33605770 DOI: 10.1103/physrevlett.126.056601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
It has been recently shown that monolayers of transition metal dichalcogenides (TMDs) in the 2H structural phase exhibit relatively large orbital Hall conductivity plateaus within their energy band gaps, where their spin Hall conductivities vanish [Canonico et al., Phys. Rev. B 101, 161409 (2020)PRBMDO2469-995010.1103/PhysRevB.101.161409; Bhowal and Satpathy, Phys. Rev. B 102, 035409 (2020)PRBMDO2469-995010.1103/PhysRevB.102.035409]. However, since the valley Hall effect (VHE) in these systems also generates a transverse flow of orbital angular momentum, it becomes experimentally challenging to distinguish between the two effects in these materials. The VHE requires inversion symmetry breaking to occur, which takes place in the TMD monolayers but not in the bilayers. We show that a bilayer of 2H-MoS_{2} is an orbital Hall insulator that exhibits a sizeable orbital Hall effect in the absence of both spin and valley Hall effects. This phase can be characterized by an orbital Chern number that assumes the value C_{L}=2 for the 2H-MoS_{2} bilayer and C_{L}=1 for the monolayer, confirming the topological nature of these orbital-Hall insulator systems. Our results are based on density functional theory and low-energy effective model calculations and strongly suggest that bilayers of TMDs are highly suitable platforms for direct observation of the orbital Hall insulating phase in two-dimensional materials. Implications of our findings for attempts to observe the VHE in TMD bilayers are also discussed.
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Affiliation(s)
- Tarik P Cysne
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói Rio de Janeiro, Brazil
| | - Marcio Costa
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói Rio de Janeiro, Brazil
| | - Luis M Canonico
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - M Buongiorno Nardelli
- Department of Physics and Department of Chemistry, University of North Texas, Denton, Texas 76203, USA
| | - R B Muniz
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói Rio de Janeiro, Brazil
| | - Tatiana G Rappoport
- Instituto de Telecomunicações, Instituto Superior Tecnico, University of Lisbon, Avenida Rovisco Pais 1, Lisboa 1049001, Portugal
- Instituto de Física, Universidade Federal do Rio de Janeiro, C.P. 68528, 21941-972 Rio de Janeiro RJ, Brazil
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Campbell DJ, Collini J, Sławińska J, Autieri C, Wang L, Wang K, Wilfong B, Eo YS, Neves P, Graf D, Rodriguez EE, Butch NP, Nardelli MB, Paglione J. Topologically driven linear magnetoresistance in helimagnetic FeP. npj Quantum Inf 2021; 6:10.1038/s41535-021-00337-2. [PMID: 37731847 PMCID: PMC10510734 DOI: 10.1038/s41535-021-00337-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 03/24/2021] [Indexed: 09/22/2023]
Abstract
The helimagnet FeP is part of a family of binary pnictide materials with the MnP-type structure, which share a nonsymmorphic crystal symmetry that preserves generic band structure characteristics through changes in elemental composition. It shows many similarities, including in its magnetic order, to isostructural CrAs and MnP, two compounds that are driven to superconductivity under applied pressure. Here we present a series of high magnetic field experiments on high-quality single crystals of FeP, showing that the resistance not only increases without saturation by up to several hundred times its zero-field value by 35 T, but that it also exhibits an anomalously linear field dependence over the entire range when the field is aligned precisely along the crystallographic c-axis. A close comparison of quantum oscillation frequencies to electronic structure calculations links this orientation to a semi-Dirac point in the band structure, which disperses linearly in a single direction in the plane perpendicular to field, a symmetry-protected feature of this entire material family. We show that the two striking features of magnetoresistance-large amplitude and linear field dependence-arise separately in this system, with the latter likely due to a combination of ordered magnetism and topological band structure.
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Affiliation(s)
- D. J. Campbell
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- Present address: LNCMI, CNRS, EMFL, Université Grenoble Alpes, INSA Toulouse, Université Toulouse Paul Sabatier, Grenoble, France
| | - J. Collini
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- NIST Center for Neutron Research, NIST, Gaithersburg, MD, USA
| | - J. Sławińska
- Department of Physics, University of North Texas, Denton, TX, USA
- Present address: Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - C. Autieri
- International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
- Consiglio Nazionale delle Ricerche CNR-SPIN, UOS Salerno, Fisciano, Salerno, Italy
| | - L. Wang
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
| | - K. Wang
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
| | - B. Wilfong
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- Department of Chemistry, University of Maryland, College Park, MD, USA
| | - Y. S. Eo
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
| | - P. Neves
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- NIST Center for Neutron Research, NIST, Gaithersburg, MD, USA
| | - D. Graf
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - E. E. Rodriguez
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- Department of Chemistry, University of Maryland, College Park, MD, USA
| | - N. P. Butch
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- NIST Center for Neutron Research, NIST, Gaithersburg, MD, USA
| | | | - J. Paglione
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD, USA
- Canadian Institute for Advanced Research, Toronto, ON, Canada
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Giannozzi P, Andreussi O, Brumme T, Bunau O, Buongiorno Nardelli M, Calandra M, Car R, Cavazzoni C, Ceresoli D, Cococcioni M, Colonna N, Carnimeo I, Dal Corso A, de Gironcoli S, Delugas P, DiStasio RA, Ferretti A, Floris A, Fratesi G, Fugallo G, Gebauer R, Gerstmann U, Giustino F, Gorni T, Jia J, Kawamura M, Ko HY, Kokalj A, Küçükbenli E, Lazzeri M, Marsili M, Marzari N, Mauri F, Nguyen NL, Nguyen HV, Otero-de-la-Roza A, Paulatto L, Poncé S, Rocca D, Sabatini R, Santra B, Schlipf M, Seitsonen AP, Smogunov A, Timrov I, Thonhauser T, Umari P, Vast N, Wu X, Baroni S. Advanced capabilities for materials modelling with Quantum ESPRESSO. J Phys Condens Matter 2017; 29:465901. [PMID: 29064822 DOI: 10.1088/1361-648x/aa8f79] [Citation(s) in RCA: 1379] [Impact Index Per Article: 197.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Quantum EXPRESSO is an integrated suite of open-source computer codes for quantum simulations of materials using state-of-the-art electronic-structure techniques, based on density-functional theory, density-functional perturbation theory, and many-body perturbation theory, within the plane-wave pseudopotential and projector-augmented-wave approaches. Quantum EXPRESSO owes its popularity to the wide variety of properties and processes it allows to simulate, to its performance on an increasingly broad array of hardware architectures, and to a community of researchers that rely on its capabilities as a core open-source development platform to implement their ideas. In this paper we describe recent extensions and improvements, covering new methodologies and property calculators, improved parallelization, code modularization, and extended interoperability both within the distribution and with external software.
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Affiliation(s)
- P Giannozzi
- Department of Mathematics, Computer Science, and Physics, University of Udine, via delle Scienze 206, I-33100 Udine, Italy
| | - O Andreussi
- Institute of Computational Sciences, Università della Svizzera Italiana, Lugano, Switzerland
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - T Brumme
- Wilhelm-Ostwald-Institute of Physical and Theoretical Chemistry, Leipzig University, Linnéstr. 2, D-04103 Leipzig, Germany
| | - O Bunau
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC University Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - M Buongiorno Nardelli
- Department of Physics and Department of Chemistry, University of North Texas, Denton, TX, United States of America
| | - M Calandra
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC University Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - R Car
- Department of Chemistry, Princeton University, Princeton, NJ 08544, United States of America
| | - C Cavazzoni
- CINECA-Via Magnanelli 6/3, I-40033 Casalecchio di Reno, Bologna, Italy
| | - D Ceresoli
- Institute of Molecular Science and Technologies (ISTM), National Research Council (CNR), I-20133 Milano, Italy
| | - M Cococcioni
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - N Colonna
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - I Carnimeo
- Department of Mathematics, Computer Science, and Physics, University of Udine, via delle Scienze 206, I-33100 Udine, Italy
| | - A Dal Corso
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
- CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Italy
| | - S de Gironcoli
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
- CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Italy
| | - P Delugas
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
| | - R A DiStasio
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States of America
| | - A Ferretti
- CNR Istituto Nanoscienze, I-42125 Modena, Italy
| | - A Floris
- School of Mathematics and Physics, College of Science, University of Lincoln, United Kingdom
| | - G Fratesi
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, I-20133 Milano, Italy
| | - G Fugallo
- ETSF, Laboratoire des Solides Irradiés, Ecole Polytechnique, F-91128 Palaiseau cedex, France
| | - R Gebauer
- The Abdus Salam International Centre for Theoretical Physics (ICTP), Strada Costiera 11, I-34151 Trieste, Italy
| | - U Gerstmann
- Department Physik, Universität Paderborn, D-33098 Paderborn, Germany
| | - F Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - T Gorni
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC University Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
| | - J Jia
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, United States of America
| | - M Kawamura
- The Institute for Solid State Physics, Kashiwa, Japan
| | - H-Y Ko
- Department of Chemistry, Princeton University, Princeton, NJ 08544, United States of America
| | - A Kokalj
- Department of Physical and Organic Chemistry, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
| | - E Küçükbenli
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
| | - M Lazzeri
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC University Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - M Marsili
- Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I-35131 Padova, Italy
| | - N Marzari
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - F Mauri
- Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - N L Nguyen
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H-V Nguyen
- Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Hanoi, Vietnam
| | - A Otero-de-la-Roza
- Department of Chemistry, University of British Columbia, Okanagan, Kelowna BC V1V 1V7, Canada
| | - L Paulatto
- IMPMC, UMR CNRS 7590, Sorbonne Universités-UPMC University Paris 06, MNHN, IRD, 4 Place Jussieu, F-75005 Paris, France
| | - S Poncé
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - D Rocca
- Université de Lorraine, CRM2, UMR 7036, F-54506 Vandoeuvre-lès-Nancy, France
- CNRS, CRM2, UMR 7036, F-54506 Vandoeuvre-lès-Nancy, France
| | - R Sabatini
- Orionis Biosciences, Newton, MA 02466, United States of America
| | - B Santra
- Department of Chemistry, Princeton University, Princeton, NJ 08544, United States of America
| | - M Schlipf
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - A P Seitsonen
- Institut für Chimie, Universität Zurich, CH-8057 Zürich, Switzerland
- Département de Chimie, École Normale Supérieure, F-75005 Paris, France
| | - A Smogunov
- SPEC, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-Sur-Yvette, France
| | - I Timrov
- Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - T Thonhauser
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109, United States of America
| | - P Umari
- Dipartimento di Fisica e Astronomia, Università di Padova, via Marzolo 8, I-35131 Padova, Italy
- CNR-IOM DEMOCRITOS, Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Italy
| | - N Vast
- Laboratoire des Solides Irradiés, École Polytechnique, CEA-DRF-IRAMIS, CNRS UMR 7642, Université Paris-Saclay, F-91120 Palaiseau, France
| | - X Wu
- Department of Physics, Temple University, Philadelphia, PA 19122-1801, United States of America
| | - S Baroni
- SISSA-Scuola Internazionale Superiore di Studi Avanzati, via Bonomea 265, I-34136 Trieste, Italy
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De Marzi G, Morici L, Muzzi L, della Corte A, Nardelli MB. Strain sensitivity and superconducting properties of Nb3Sn from first principles calculations. J Phys Condens Matter 2013; 25:135702. [PMID: 23478497 DOI: 10.1088/0953-8984/25/13/135702] [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: 06/01/2023]
Abstract
Using calculations from first principles based on density-functional theory we have studied the strain sensitivity of the A15 superconductor Nb3Sn. The Nb3Sn lattice cell was deformed in the same way as observed experimentally on multifilamentary, technological wires subject to loads applied along their axes. The phonon dispersion curves and electronic band structures along different high-symmetry directions in the Brillouin zone were calculated, at different levels of applied strain, ε, on both the compressive and the tensile side. Starting from the calculated averaged phonon frequencies and electron-phonon coupling, the superconducting characteristic critical temperature of the material, T(c), has been calculated by means of the Allen-Dynes modification of the McMillan formula. As a result, the characteristic bell-shaped T(c) versus ε curve, with a maximum at zero intrinsic strain, and with a slight asymmetry between the tensile and compressive sides, has been obtained. These first-principle calculations thus show that the strain sensitivity of Nb3Sn has a microscopic and intrinsic origin, originating from shifts in the Nb3Sn critical surface. In addition, our computations show that variations of the superconducting properties of this compound are correlated to stress-induced changes in both the phononic and electronic properties. Finally, the strain function describing the strain sensitivity of Nb3Sn has been extracted from the computed T(c)(ε) curve, and compared to experimental data from multifilamentary, composite wires. Both curves show the expected bell-shaped behavior, but the strain sensitivity of the wire is enhanced with respect to the theoretical predictions for bulk, perfectly binary and stoichiometric Nb3Sn. An understanding of the origin of this difference might open potential pathways towards improvement of the strain tolerance in such systems.
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Affiliation(s)
- G De Marzi
- EURATOM-ENEA Association on Fusion, Frascati RM, Italy.
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Chen Y, Jayasekera T, Calzolari A, Kim KW, Nardelli MB. Thermoelectric properties of graphene nanoribbons, junctions and superlattices. J Phys Condens Matter 2010; 22:372202. [PMID: 21403189 DOI: 10.1088/0953-8984/22/37/372202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Using model interaction Hamiltonians for both electrons and phonons and Green's function formalism for ballistic transport, we have studied the thermal conductance and the thermoelectric properties of graphene nanoribbons (GNR), GNR junctions and periodic superlattices. Among our findings we have established the role that interfaces play in determining the thermoelectric response of GNR systems both across single junctions and in periodic superlattices. In general, increasing the number of interfaces in a single GNR system increases the peak ZT values that are thus maximized in a periodic superlattice. Moreover, we proved that the thermoelectric behavior is largely controlled by the width of the narrower component of the junction. Finally, we have demonstrated that chevron-type GNRs recently synthesized should display superior thermoelectric properties.
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Affiliation(s)
- Y Chen
- Department of Physics, North Carolina State University, Raleigh, NC 27695-7518, USA
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Ranjan V, Yu L, Nakhmanson S, Bernholc J, Nardelli MB. Polarization effects and phase equilibria in high-energy-density polyvinylidene-fluoride-based polymers. Acta Crystallogr A 2010; 66:553-7. [PMID: 20720320 DOI: 10.1107/s0108767310026358] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 07/04/2010] [Indexed: 11/10/2022] Open
Abstract
Using first-principles calculations, the phase diagrams of polyvinylidene fluoride (PVDF) and its copolymers under an applied electric field are studied and phase transitions between their nonpolar alpha and polar beta phases are discussed. The results show that the degree of copolymerization is a crucial parameter controlling the structural phase transition. In particular, for tetrafluoroethylene (TeFE) concentration above 12%, PVDF-TeFE is stabilized in the beta phase, whereas the alpha phase is stable for lower concentrations. As larger electric fields are applied, domains with smaller concentrations (< or = 12%) undergo a transition from the alpha to the beta phase until a breakdown field of approximately 600 MV m(-1) is reached. These structural phase transitions can be exploited for efficient storage of electrical energy.
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Affiliation(s)
- V Ranjan
- Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, NC 27695-7518, USA
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Jayasekera T, Kong BD, Kim KW, Buongiorno Nardelli M. Band engineering and magnetic doping of epitaxial graphene on SiC (0001). Phys Rev Lett 2010; 104:146801. [PMID: 20481952 DOI: 10.1103/physrevlett.104.146801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Indexed: 05/29/2023]
Abstract
Using calculations from first principles we show how specific interface modifications can lead to a fine-tuning of the doping and band alignment in epitaxial graphene on SiC. Upon different choices of dopants, we demonstrate that one can achieve a variation of the valence band offset between the graphene Dirac point and the valence band edge of SiC up to 1.5 eV. Finally, via appropriate magnetic doping one can induce a half-metallic behavior in the first graphene monolayer. These results clearly establish the potential for graphene utilization in innovative electronic and spintronic devices.
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Affiliation(s)
- Thushari Jayasekera
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-7518, USA
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Abstract
The enormous potential of carbon nanotubes (CNTs) as primary components in electronic devices and NEMS necessitates the understanding and predicting of the effects of mechanical deformation on electron transport in CNTs. In principle, detailed atomic/electronic calculations can provide both the deformed configuration and the resulting electrical transport behavior of the CNT. However, the computational expense of these simulations limits the size of the CNTs that can be studied with this technique, and a direct analysis of CNTs of the dimension used in nanoelectronic devices seems prohibitive at the present. Here a computationally effective mixed finite element (FE)/tight-binding (TB) approach able to simulate the electromechanical behavior of CNT devices is presented. The TB code is carefully designed to realize orders-of-magnitude reduction in computational time in calculating deformation-induced changes in electrical transport properties of the nanotubes. The FE-TB computational approach is validated in a simulation of laboratory experiments on a multiwall CNT and then used to demonstrate the role of the multiwall structure in providing robustness to conductivity in the event of imposed mechanical deformations.
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Affiliation(s)
- A Pantano
- Dipartimento di Meccanica, Università degli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy.
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10
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Nuñez M, Buongiorno Nardelli M. Onset of ferrielectricity and the hidden nature of nanoscale polarization in ferroelectric thin films. Phys Rev Lett 2008; 101:107603. [PMID: 18851257 DOI: 10.1103/physrevlett.101.107603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Indexed: 05/26/2023]
Abstract
Using calculations from first principles and the concept of layer polarization, we have elucidated the nanoscale organization and local polarization in ferroelectric thin films between metallic contacts. The profile of the local polarization for different film thicknesses unveils a peculiar spatial pattern of atomic layers with uncompensated dipoles in what was originally thought to be a ferroelectric domain. This effectively ferrielectric behavior is induced by the dominant roles of the interfaces at such reduced dimensionality and can be interpreted using a simple classical model where the latter are explicitly taken into account.
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Affiliation(s)
- Matías Nuñez
- Center for High Performance Simulation and Department Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
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Bernholc J, Lu W, Nakhmanson SM, Hahn P, Meunier V, Buongiorno Nardelli M, Schmidt W. Atomic scale design of nanostructures. Mol Phys 2007. [DOI: 10.1080/00268970701189186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Stekolnikov AA, Seino K, Bechstedt F, Wippermann S, Schmidt WG, Calzolari A, Nardelli MB. Hexagon versus trimer formation in in nanowires on Si(111): energetics and quantum conductance. Phys Rev Lett 2007; 98:026105. [PMID: 17358624 DOI: 10.1103/physrevlett.98.026105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Indexed: 05/14/2023]
Abstract
The structural and electronic properties of the quasi-one-dimensional In/Si(111) surface system are calculated from first principles. It is found that the symmetry lowering of the In chains is energetically favorable, provided neighboring nanowires are correlated, giving rise to a doubling of the surface unit cell both along and perpendicular to the chain direction. The recently suggested formation of hexagons within the In nanowires [C. González, F. Flores, and J. Ortega, Phys. Rev. Lett. 96, 136101 (2006)]--in clear contrast to the trimer formation proposed earlier-drastically modifies the electron transport along the In chains, in agreement with experiment.
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Affiliation(s)
- A A Stekolnikov
- Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena, Germany
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Kostov MK, Santiso EE, George AM, Gubbins KE, Nardelli MB. Dissociation of water on defective carbon substrates. Phys Rev Lett 2005; 95:136105. [PMID: 16197155 DOI: 10.1103/physrevlett.95.136105] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Indexed: 05/04/2023]
Abstract
Using calculations from first principles, we found that water can dissociate over defective sites in graphene or nanotubes following many possible reaction pathways, some of which have activation barriers lower than half the value for the dissociation of bulk water. This reduction is caused by spin selection rules that allow the system to remain on the same spin surface throughout the reaction.
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Affiliation(s)
- M K Kostov
- Center for High Performance Simulation and Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, USA
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14
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Abstract
Novel carbon nanotube-metal cluster structures are proposed as prototype systems for molecular recognition at the nanoscale. Ab initio calculations show that already the bare nanotube cluster system displays some specificity because the adsorption of ammonia on a carbon nanotube-Al cluster system is easily detected electrically, while diborane adsorption does not provide an electrical signature. Since there are well-established procedures for attaching molecular receptors to metal clusters, these results provide a "proof-of-principle" for the development of novel, high-specificity molecular sensors.
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Affiliation(s)
- Q Zhao
- Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA.
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15
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Ferretti A, Calzolari A, Di Felice R, Manghi F, Caldas MJ, Buongiorno Nardelli M, Molinari E. First-principles theory of correlated transport through nanojunctions. Phys Rev Lett 2005; 94:116802. [PMID: 15903879 DOI: 10.1103/physrevlett.94.116802] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Indexed: 05/02/2023]
Abstract
We report the inclusion of electron-electron correlation in the calculation of transport properties within an ab initio scheme. A key step is the reformulation of Landauer's approach in terms of an effective transmittance for the interacting electron system. We apply this framework to analyze the effect of short-range interactions on Pt atomic wires and discuss the coherent and incoherent correction to the mean-field approach.
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Affiliation(s)
- A Ferretti
- INFM National Center on nanoStructures and bioSystems at Surfaces (S3) and Dipartimento di Fisica, Università di Modena e Reggio Emilia, 41100 Modena, Italy
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16
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Nakhmanson SM, Nardelli MB, Bernholc J. Ab initio studies of polarization and piezoelectricity in vinylidene fluoride and BN-based polymers. Phys Rev Lett 2004; 92:115504. [PMID: 15089148 DOI: 10.1103/physrevlett.92.115504] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Indexed: 05/24/2023]
Abstract
Highly piezoelectric and pyroelectric phases of boron-nitrogen-based polymers have been designed from first principles. They offer excellent electrical and structural properties, with up to 100% improvement in the piezoelectic response and an enhanced thermal stability with respect to polyvinylidene fluoride (PVDF). Since methods for their synthesis are readily available, these polymers are extremely promising for numerous technological applications, rivaling the properties of ferroelectric ceramics and superseding PVDF-based materials in high-performance devices.
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Affiliation(s)
- S M Nakhmanson
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
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17
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Edmonds KW, Bogusławski P, Wang KY, Campion RP, Novikov SN, Farley NRS, Gallagher BL, Foxon CT, Sawicki M, Dietl T, Buongiorno Nardelli M, Bernholc J. Mn interstitial diffusion in (ga,mn)as. Phys Rev Lett 2004; 92:037201. [PMID: 14753901 DOI: 10.1103/physrevlett.92.037201] [Citation(s) in RCA: 25] [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: 06/24/2003] [Indexed: 05/24/2023]
Abstract
We present a combined theoretical and experimental study of the ferromagnetic semiconductor (Ga,Mn)As which explains the remarkably large changes observed on low-temperature annealing. Careful control of the annealing conditions allows us to obtain samples with ferromagnetic transition temperatures up to 159 K. Ab initio calculations, in situ Auger spectroscopy, and resistivity measurements during annealing show that the observed changes are due to out diffusion of Mn interstitials towards the surface, governed by an energy barrier of 0.7-0.8 eV. Electric fields induced by Mn acceptors have a significant effect on the diffusion.
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Affiliation(s)
- K W Edmonds
- School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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18
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McKee RA, Walker FJ, Nardelli MB, Shelton WA, Stocks GM. The interface phase and the Schottky barrier for a crystalline dielectric on silicon. Science 2003; 300:1726-30. [PMID: 12805542 DOI: 10.1126/science.1083894] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The barrier height for electron exchange at a dielectric-semiconductor interface has long been interpreted in terms of Schottky's theory with modifications from gap states induced in the semiconductor by the bulk termination. Rather, we show with the structure specifics of heteroepitaxy that the electrostatic boundary conditions can be set in a distinct interface phase that acts as a "Coulomb buffer." This Coulomb buffer is tunable and will functionalize the barrier-height concept itself.
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Affiliation(s)
- R A McKee
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Abstract
The transfer of electrons from one material to another is usually described in terms of energy conservation, with no attention being paid to momentum conservation. Here we present results on the junction resistance between a carbon nanotube and a graphite substrate and show that details of momentum conservation also can change the contact resistance. By changing the angular alignment of the atomic lattices, we found that contact resistance varied by more than an order of magnitude in a controlled and reproducible fashion, indicating that momentum conservation, in addition to energy conservation, can dictate the junction resistance in graphene systems such as carbon nanotube junctions and devices.
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Affiliation(s)
- S Paulson
- Department of Physics and Astronomy, Department of Computer Science, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA
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Nardelli MB, Cvetko D, Floreano L, Gotter R, Morgante A, Peloi M, Tommasini F, Danieli R, Rossini S, Taliani C, Zamboni R. Ordering of a prototypical conjugated molecular system during monolayer growth on the (1 x 2)-Au(110) surface. Phys Rev B Condens Matter 1996; 53:1095-1098. [PMID: 9983564 DOI: 10.1103/physrevb.53.1095] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Nardelli MB, Baroni S, Giannozzi P. Phonon softening and high-pressure low-symmetry phases of cesium iodide. Phys Rev Lett 1992; 69:1069-1072. [PMID: 10047115 DOI: 10.1103/physrevlett.69.1069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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25
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De Capoa A, Pelliccia F, Marlekaj P, Ciofi-Luzzatto AR, Buongiorno Nardelli M. Silver positivity of the NORs during embryonic development of Xenopus laevis. Exp Cell Res 1983; 147:472-8. [PMID: 6193984 DOI: 10.1016/0014-4827(83)90231-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Transcriptional activity of ribosomal RNA (rRNA) genes is detectable around blastula-gastrula transition during the embryonic development of amphibians and other non-mammalian systems. The silver staining reaction, known to selectively stain transcriptionally active nucleolus organizer regions (NORs) both in interphase and metaphase chromosomes allowed us to follow the activation of the NORs during the embryonic development of Xenopus laevis.
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