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Khan W, Kushwaha AK, Al-Amer R, Alanazi N, Alqahtani HR, Al-Qaisi S, Faizan M, Haq BU, Laref A, Alghamdi EA, Nya FT, Amine Monir ME, Chowdhury S. Electronic, optical, and thermoelectric characteristics of (Ae) xFBiS 2 (Ae=Sr, Ba, and x=1.7) layered materials useful in optical modulator devices. J Mol Graph Model 2024; 129:108729. [PMID: 38479238 DOI: 10.1016/j.jmgm.2024.108729] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/04/2024] [Accepted: 02/14/2024] [Indexed: 04/15/2024]
Abstract
The recent discovery of superconductivity behavior in the mother BiS2-layered compounds has captivated the attention of several physicists. The crystal structure of superconductors with alternate layers of BiS2 is homologous to that of cuprates and Fe-based superconductors. The full-potential linearized augmented plane-wave (FP-LAPW) technique was utilized to investigate the electronic structures and density of states in the vicinity of the Fermi energy of SrFBiS2 and BaFBiS2 compounds under the electron carriers doping. The introduction of electron doping (carries doping) reveals that the host compounds SrFBiS2 and BaFBiS2 exhibit features indicative of superconductivity. This carrier doping of SrFBiS2 and BaFBiS2 compounds (electron-doped) has a significant impact on the lowest conduction states near the Fermi level for the emergence of the superconducting aspect. The electron doping modifies and induces changes in the electronic structures with superconducting behavior in (Ae)1.7FBiS2(Ae=Sr,Ba) compounds. A Fermi surface nesting occurred under the modification of electrons (carriers) doping in the host compounds SrFBiS2 and BaFBiS2. Furthermore, the optical characteristics of the carrier-doped SrFBiS2 and BaFBiS2 compounds are simulated. Due to the anisotropic behavior, the optical properties of these materials based on BiS2 demonstrate a pronounced polarization dependency. The starting point at zero photon energy in the infrared region is elucidated by considering the Drude features in the optical conductivity spectra of SrFBiS2 and BaFBiS2 compounds, when the electron carriers doping is applied. It was clearly noticed that the spin-orbit coupling (SOC) influences the electronic band structures, density of states, Femi surface, and optical features because of the heavy Bismuth atom, which may disclose fascinating aspects. Further, we conducted simulations to assess the thermoelectric properties of these mother compounds. The two BiS2-layered compounds could be suitable for practical thermoelectric purposes and are highlighted through assessment of electrical conductivity, thermal conductivity, Seebeck coefficient, and power factor. As a result, we propose that the mechanisms of superconducting behavior in BiS2 family may pave new avenues for investigating the field of unconventional superconductivity. It may also provide new insights into the origin of high-Tc superconductivity nature.
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Affiliation(s)
- W Khan
- Department of Physics, Bacha Khan University, Charsada, Pakistan.
| | - A K Kushwaha
- Department of Physics, S.I.G. Govt. P.G. College, Lalganj, Mirzapur, U.P., India; Department of Physics, K.N. Govt. P.G. College, Gyanpur, Bhadohi, 221304, U.P., India
| | - R Al-Amer
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi Arabia
| | - Nadyah Alanazi
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi Arabia
| | - H R Alqahtani
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi Arabia
| | - Samah Al-Qaisi
- Palestinian Ministry of Education and Higher Education, Nablus, Palestine
| | - Muhammad Faizan
- College of Materials Science and Engineering Jilin University, Changchun, China
| | - Bakhtiar Ul Haq
- Faculty of Science Education, Jeju National University, Jeju, 63243, Republic of Korea; Advanced Functional Materials & Optoelectronics Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha, Kingdom of Saudi Arabia
| | - A Laref
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi Arabia.
| | - Eman A Alghamdi
- Department of Physics and Astronomy, College of Science, King Saud University, Riyadh, 11451, Kingdom of Saudi Arabia
| | - Fridolin Tchangnwa Nya
- University of Maroua, High National College of Technology, Department of Energy and Environment, Cameroon; University of Maroua, Faculty of Science, Department of Physics, Materials Science Laboratory, P.O. Box 814, Maroua, Cameroon
| | - Mohammed El Amine Monir
- Faculty of the Exact Sciences, Mustapha Stambouli University of Mascara, B.P. 305, 29000, Mascara, Algeria
| | - Shahariar Chowdhury
- Faculty of Environmental Management, Prince of Songkla University, Songkhla, 90110, Thailand; Environmental Assessment and Technology for Hazardous Waste Management Research Centre, Faculty of Environmental Management, Prince of Songkla University, Songkhla, 90110, Thailand
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Pouget JP, Canadell E. Structural approach to charge density waves in low-dimensional systems: electronic instability and chemical bonding. Rep Prog Phys 2024; 87:026501. [PMID: 38052072 DOI: 10.1088/1361-6633/ad124f] [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] [Received: 06/15/2023] [Accepted: 12/05/2023] [Indexed: 12/07/2023]
Abstract
The charge density wave (CDW) instability, usually occurring in low-dimensional metals, has been a topic of interest for longtime. However, some very fundamental aspects of the mechanism remain unclear. Recently, a plethora of new CDW materials, a substantial fraction of which is two-dimensional or even three-dimensional, has been prepared and characterised as bulk and/or single-layers. As a result, the need for revisiting the primary mechanism of the instability, based on the electron-hole instability established more than 50 years ago for quasi-one-dimensional (quasi-1D) conductors, has clearly emerged. In this work, we consider a large number of CDW materials to revisit the main concepts used in understanding the CDW instability, and emphasise the key role of the momentum dependent electron-phonon coupling in linking electronic and structural degrees of freedom. We argue that for quasi-1D systems, earlier weak coupling theories work appropriately and the energy gain due to the CDW and the concomitant periodic lattice distortion (PLD) remains primarily due to a Fermi surface nesting mechanism. However, for materials with higher dimensionality, intermediate and strong coupling regimes are generally at work and the modification of the chemical bonding network by the PLD is at the heart of the instability. We emphasise the need for a microscopic approach blending condensed matter physics concepts and state-of-the-art first-principles calculations with quite fundamental chemical bonding ideas in understanding the CDW phenomenon in these materials.
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Affiliation(s)
- Jean-Paul Pouget
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405 Orsay, France
| | - Enric Canadell
- Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain, and Royal Academy of Sciences and Arts of Barcelona, Chemistry Section, La Rambla 115, 08002 Barcelona, Spain
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Kong P, Li G, Yang Z, Wen C, Qi Y, Felser C, Yan S. Fully Two-Dimensional Incommensurate Charge Modulation on the Pd-Terminated Polar Surface of PdCoO 2. Nano Lett 2022; 22:5635-5640. [PMID: 35838660 DOI: 10.1021/acs.nanolett.1c03857] [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: 06/15/2023]
Abstract
Here, we use low-temperature scanning tunneling microscopy and spectroscopy to study the polar surfaces of PdCoO2. On the CoO2-terminated polar surface, we detect the quasiparticle interference pattern originating from the Rashba-like spin-split surface states. On the well-ordered Pd-terminated polar surface, we observe a regular lattice that has a larger lattice constant than the atomic lattice of PdCoO2. In comparison with the shape of the hexagonal Fermi surface on the Pd-terminated surface, we identify this regular lattice as a fully two-dimensional incommensurate charge modulation that is driven by the Fermi surface nesting. More interestingly, we also find the moiré pattern induced by the interference between the two-dimensional incommensurate charge modulation in the Pd layer and its atomic lattice. Our results not only show a new charge modulation on the Pd surface of PdCoO2 but also pave the way for fully understanding the novel electronic properties of this material.
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Affiliation(s)
- Pengfei Kong
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Guowei Li
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- CAS Key Laboratory of Magnetic Materials and Devices, and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- University of Chinese Academy of Sciences, 19 A Yuquan Road, Shijingshan District, Beijing 100049, China
| | - Zhongzheng Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chenhaoping Wen
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, China
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Shichao Yan
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China
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Biswas S. Non-Maxwell-Boltzmann dependence of channel carrier concentration in a quasi one dimensional charge density wave channel in the ballistic transport regime. J Phys Condens Matter 2022; 34:195302. [PMID: 35130518 DOI: 10.1088/1361-648x/ac5279] [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] [Received: 10/31/2021] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
With the aid of a coherent transport model utilizing the non-equilibrium Green function approach, a three terminal device with metallic gate, source and drain and a quasi one dimensional charge density wave (CDW) channel is simulated focussing on the transistor behaviour brought about by a sweep of the channel potential or equivalently the chemical potential in the channel. The channel is strongly insulating only at half-filling and moving to lower and higher carrier concentrations both incur a mean field phase transition to a conducting state. With the aid of conductance calculations for a pinned CDW condensate, we present calculations for the sub-threshold slope in terms of the hopping parameter or equivalently the width of the tight-binding chain. The effects of source to drain bias and length are examined. The conductance profiles are analyed in relation to transmission profiles. The observed CDW profiles are explained in terms of filling and Fermi surface nesting. Boundary conditions, gap equations and response functions are shown to reveal the commensurability conditions and size of the transport gap. The channel carrier concentration is modulated in an athermal (non-Maxwellian-Boltzmann) fashion, thereby making it an interesting prospect for steep transistors.
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Affiliation(s)
- Saumya Biswas
- Department of Physics, University of Oregon, Eugene, OR 97403, United States of America
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Divilov S, Mayo SG, Soler JM, Yndurain F. Critical analysis of the response function in low-dimensional materials. J Phys Condens Matter 2021; 33:295701. [PMID: 33636715 DOI: 10.1088/1361-648x/abea41] [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] [Received: 01/12/2021] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
The presence of sharp peaks in the real part of the static dielectric response function are usually accepted as indication of charge or spin instabilities in a material. However, there are misconceptions that Fermi surface (FS) nesting guarantees a peak in the response function like in one-dimensional systems, and, in addition, response function matrix elements between empty and occupied states are usually considered of secondary importance and typically set to unity like in the free electron gas case. In this work, we explicitly show, through model systems and real materials, within the framework of density functional theory, that predictions about the peaks in the response function, using FS nesting and constant matrix elements yields erroneous conclusions. We find that the inclusion of the matrix elements completely alters the structure of the response function. In all the cases studied other than the one-dimensional case we find that the inclusion of matrix elements washes out the structure found with constant matrix elements. Our conclusion is that it is imperative to calculate the full response function, with matrix elements, when making predictions about instabilities in novel materials.
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Affiliation(s)
- Simon Divilov
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Sara G Mayo
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Jose M Soler
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Felix Yndurain
- Departamento de Física de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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Fleischmann M, Gupta R, Wullschläger F, Theil S, Weckbecker D, Meded V, Sharma S, Meyer B, Shallcross S. Perfect and Controllable Nesting in Minimally Twisted Bilayer Graphene. Nano Lett 2020; 20:971-978. [PMID: 31884797 DOI: 10.1021/acs.nanolett.9b04027] [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] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Parallel ("nested") regions of a Fermi surface (FS) drive instabilities of the electron fluid, for example, the spin density wave in elemental chromium. In one-dimensional materials, the FS is trivially fully nested (a single nesting vector connects two "Fermi dots"), while in higher dimensions only a fraction of the FS consists of parallel sheets. We demonstrate that the tiny angle regime of twist bilayer graphene (TBLG) possesses a phase, accessible by interlayer bias, in which the FS consists entirely of nestable "Fermi lines", the first example of a completely nested FS in a two-dimensional (2D) material. This nested phase is found both in the ideal as well as relaxed structure of the twist bilayer. We demonstrate excellent agreement with recent STM images of topological states in this material and elucidate the connection between these and the underlying Fermiology. We show that the geometry of the Fermi lines network is controllable by the strength of the applied interlayer bias, and thus TBLG offers unprecedented access to the physics of FS nesting in 2D materials.
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Affiliation(s)
- Maximilian Fleischmann
- Lehrstuhl für Theoretische Festkörperphysik , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstraße 7-B2 , 91058 Erlangen , Germany
| | - Reena Gupta
- Lehrstuhl für Theoretische Festkörperphysik , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstraße 7-B2 , 91058 Erlangen , Germany
| | - Florian Wullschläger
- Interdisciplinary Center for Molecular Materials (ICMM) and Computer-Chemistry-Center (CCC) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Nägelsbachstraße 25 , 91052 Erlangen , Germany
| | - Simon Theil
- Lehrstuhl für Theoretische Festkörperphysik , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstraße 7-B2 , 91058 Erlangen , Germany
| | - Dominik Weckbecker
- Lehrstuhl für Theoretische Festkörperphysik , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstraße 7-B2 , 91058 Erlangen , Germany
| | - Velimir Meded
- Intitute of Nanotechnology , Karlsruhe Institute of Technology (KIT) , Hermann-von-Helmholtz-Platz 1 , 76344 Eggenstein-Leopoldshafen , Germany
| | - Sangeeta Sharma
- Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy , Max-Born Straße 2A , 12489 Berlin , Germany
| | - Bernd Meyer
- Interdisciplinary Center for Molecular Materials (ICMM) and Computer-Chemistry-Center (CCC) , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Nägelsbachstraße 25 , 91052 Erlangen , Germany
| | - Samuel Shallcross
- Lehrstuhl für Theoretische Festkörperphysik , Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Staudtstraße 7-B2 , 91058 Erlangen , Germany
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Zhu GY, Xiang T, Zhang GM. Inter-valley spiral order in the Mott insulating state of a heterostructure of trilayer graphene-boron nitride. Sci Bull (Beijing) 2018; 63:1087-1091. [PMID: 36658986 DOI: 10.1016/j.scib.2018.06.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 01/21/2023]
Abstract
Recent experiment has shown that the ABC-stacked trilayer graphene-boron nitride Moire super-lattice at half-filling is a Mott insulator. Based on symmetry analysis and effective band structure calculation, we propose a valley-contrasting chiral tight-binding model with local Coulomb interaction to describe this Moire super-lattice system. By matching the positions of van Hove points in the low-energy effective bands, the valley-contrasting staggered flux per triangle is determined around π/2. When the valence band is half-filled, the Fermi surfaces are found to be perfectly nested between the two valleys. Such an effect can induce an inter-valley spiral order with a gap in the charge excitations, indicating that the Mott insulating behavior observed in the trilayer graphene-boron nitride Moire super-lattice results predominantly from the inter-valley scattering.
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Affiliation(s)
- Guo-Yi Zhu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China
| | - Tao Xiang
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Guang-Ming Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
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