The structural, electronic, vibrational, and optical properties of 2D- 2H-WTe2 monolayer are investigated using density functional theory with respect to a plane wave ultrasoft pseudopotentials (PW-USPPs) in a generalized gradient approximation (GGA) and with the Hubbard potential (GGA + U). The equilibrium state properties such as lattice parameters, unit cell volume, bulk modulus, and its derivative are determined. The band gap values of monolayer 2H-WTe2 are investigated for unstrained, 2% biaxial compression, and biaxial tensile stress using GGA, respectively. The obtained band gap values of 2H-WTe2 with respect to GGA are 1.043, 1.1487, and 0.9439 eV for unstrained, biaxial compression, and tensile strain, respectively. Moreover, the band gap values determined using Hubbard correction (GGA + U) are 1.1089 eV (unstrained), 1.2332 eV (2% biaxial compression), and 0.9945 eV (2% biaxial tensile stress), respectively. The band gap value obtained using Hubbard correction predicts the experimental value more precisely. The projected density of state shows W (3d) orbital is more dominant both in the valence band maximum and conduction band minimum. Moreover, a small amount of tensile or compressive strain is used to tune the band gap of the monolayer without affecting its direct band gap nature. In addition to this, the phonon dispersion and optical properties are discussed for tensile strain, unstrained, and compressive strain, respectively.
{"title":"Structural, Electronic, Dynamic, and Optical Properties of 2D Monolayer Tungsten Telluride (2H-WTe2) under Small Biaxial Strain Using Density Functional Theory (DFT and DFT + U)","authors":"Mulugeta Woldesenbet, Nebiyu Debelo, Menberu Woldemariam","doi":"10.1155/2023/3179210","DOIUrl":"https://doi.org/10.1155/2023/3179210","url":null,"abstract":"The structural, electronic, vibrational, and optical properties of 2D- 2H-WTe2 monolayer are investigated using density functional theory with respect to a plane wave ultrasoft pseudopotentials (PW-USPPs) in a generalized gradient approximation (GGA) and with the Hubbard potential (GGA + U). The equilibrium state properties such as lattice parameters, unit cell volume, bulk modulus, and its derivative are determined. The band gap values of monolayer 2H-WTe2 are investigated for unstrained, 2% biaxial compression, and biaxial tensile stress using GGA, respectively. The obtained band gap values of 2H-WTe2 with respect to GGA are 1.043, 1.1487, and 0.9439 eV for unstrained, biaxial compression, and tensile strain, respectively. Moreover, the band gap values determined using Hubbard correction (GGA + U) are 1.1089 eV (unstrained), 1.2332 eV (2% biaxial compression), and 0.9945 eV (2% biaxial tensile stress), respectively. The band gap value obtained using Hubbard correction predicts the experimental value more precisely. The projected density of state shows W (3d) orbital is more dominant both in the valence band maximum and conduction band minimum. Moreover, a small amount of tensile or compressive strain is used to tune the band gap of the monolayer without affecting its direct band gap nature. In addition to this, the phonon dispersion and optical properties are discussed for tensile strain, unstrained, and compressive strain, respectively.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"176 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138524061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Vijayalakshmi, T. Ramachandran, G. Jaiganesh, G. Kalpana, F. Hamed
We present a comprehensive investigation of the electromagnetic properties of CdAB2 compounds, where A represents Cr, Mn, or Fe, and B denotes P or As. To investigate the spin-polarized behavior of these compounds the A atoms were substituted at the Group IV (Ge) position in CdGeB2 in the chalcopyrite crystal structure. Our results reveal that all the CdAB2 compounds exhibit compelling spin-splitting of energy states near the Fermi level (EF). Notably, CdAB2 materials with A = Cr and Mn exhibit intriguing half-metallic ferromagnetic (HMF) characteristics, with the calculated total magnetic moments of 2.00 and 3.00 µB/f.u., respectively. The HMF properties originated in CdAB2 (A = Cr and Mn; B = P, As) these compounds owing to the hybridization of partially filled -3d(t2g) states of A atoms with the p-states of B (P, As) atoms, with minor contributions from Cd’s-like states. In contrast, CdFeB2 displays distinct behavior, demonstrating spin-splitting of energy levels around the EF indicative of a stable ferromagnetic (FM) state and the absence of HMF at their equilibrium volume. The calculated total magnetic moments for CdFeP2 and CdFeAs2 are about 1.83 (1.64 µB/f.u.) and 1.94 µB/f.u. (1.84 µB/f.u.) under generalized gradient approximation (GGA) (local spin density approximation (LSDA)) approximations, respectively. Perhaps these CdAB2 compounds (A = Cr and Mn; B = P, As) with HMF characteristic within both LSDA and GGA formalisms makes them highly promising candidates for spin injectors in the spintronic device applications. Furthermore, their semiconducting nature renders CdCrB2 and CdMnB2 materials compatible with silicon and other semiconducting lattices, enhancing their potential practical applications in the spintronic technologies. In conclusion, this study presents a thorough exploration of the robust electronic and magnetic properties of CdAB2 chalcopyrites, offering exciting prospects for their utilization in the future spintronic applications.
{"title":"Unveiling the Robust Struct-Electromagnetic Characteristics of CdAB2 Chalcopyrite (A = Cr, Mn, Fe; B = P, As): A Comprehensive Ab-Initio Study","authors":"D. Vijayalakshmi, T. Ramachandran, G. Jaiganesh, G. Kalpana, F. Hamed","doi":"10.1155/2023/1754324","DOIUrl":"https://doi.org/10.1155/2023/1754324","url":null,"abstract":"We present a comprehensive investigation of the electromagnetic properties of CdAB2 compounds, where A represents Cr, Mn, or Fe, and B denotes P or As. To investigate the spin-polarized behavior of these compounds the A atoms were substituted at the Group IV (Ge) position in CdGeB2 in the chalcopyrite crystal structure. Our results reveal that all the CdAB2 compounds exhibit compelling spin-splitting of energy states near the Fermi level (EF). Notably, CdAB2 materials with A = Cr and Mn exhibit intriguing half-metallic ferromagnetic (HMF) characteristics, with the calculated total magnetic moments of 2.00 and 3.00 µB/f.u., respectively. The HMF properties originated in CdAB2 (A = Cr and Mn; B = P, As) these compounds owing to the hybridization of partially filled -3d(t2g) states of A atoms with the p-states of B (P, As) atoms, with minor contributions from Cd’s-like states. In contrast, CdFeB2 displays distinct behavior, demonstrating spin-splitting of energy levels around the EF indicative of a stable ferromagnetic (FM) state and the absence of HMF at their equilibrium volume. The calculated total magnetic moments for CdFeP2 and CdFeAs2 are about 1.83 (1.64 µB/f.u.) and 1.94 µB/f.u. (1.84 µB/f.u.) under generalized gradient approximation (GGA) (local spin density approximation (LSDA)) approximations, respectively. Perhaps these CdAB2 compounds (A = Cr and Mn; B = P, As) with HMF characteristic within both LSDA and GGA formalisms makes them highly promising candidates for spin injectors in the spintronic device applications. Furthermore, their semiconducting nature renders CdCrB2 and CdMnB2 materials compatible with silicon and other semiconducting lattices, enhancing their potential practical applications in the spintronic technologies. In conclusion, this study presents a thorough exploration of the robust electronic and magnetic properties of CdAB2 chalcopyrites, offering exciting prospects for their utilization in the future spintronic applications.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"45 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139253409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have carried out molecular dynamics (MD) simulation techniques to study the diffusion coefficient of interlayer molecules at different temperature. We have focused on the translation dynamics of water in bihydrated states within the context of water dynamics in clays. We concentrated on temperatures between 293 and 350 K, i.e., the range important to daily life wastewater handling. A natural clay has been modified as a synthetic clay called fluorohectorite clay, and the properties are studied using MD simulations, the result of which allows us to understand the determining parameters through a comparison with experiment values. The activation energy is determined by our simulation to be between [0.09−0.17] eV per particle. The calculated diffusion constants are in the order of 10−5 cm2s−1. The simulation results are in a good agreement with experiments for the relevant set of conditions, and give insight into the origin of the observed dynamics.
{"title":"Temperature Dependence Study of Water Dynamics in Fluorohectorite Clays Using Molecular Dynamics Simulations","authors":"H. O. Mohammed, K. N. Nigussa","doi":"10.1155/2023/7005896","DOIUrl":"https://doi.org/10.1155/2023/7005896","url":null,"abstract":"We have carried out molecular dynamics (MD) simulation techniques to study the diffusion coefficient of interlayer molecules at different temperature. We have focused on the translation dynamics of water in bihydrated states within the context of water dynamics in clays. We concentrated on temperatures between 293 and 350 K, i.e., the range important to daily life wastewater handling. A natural clay has been modified as a synthetic clay called fluorohectorite clay, and the properties are studied using MD simulations, the result of which allows us to understand the determining parameters through a comparison with experiment values. The activation energy <svg height=\"11.927pt\" style=\"vertical-align:-3.291101pt\" version=\"1.1\" viewbox=\"-0.0498162 -8.6359 13.2655 11.927\" width=\"13.2655pt\" xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g transform=\"matrix(.013,0,0,-0.013,0,0)\"></path></g><g transform=\"matrix(.0091,0,0,-0.0091,7.943,3.132)\"></path></g></svg> is determined by our simulation to be between [0.09−0.17] eV per particle. The calculated diffusion constants are in the order of 10<sup>−5</sup> cm<sup>2</sup>s<sup>−1</sup>. The simulation results are in a good agreement with experiments for the relevant set of conditions, and give insight into the origin of the observed dynamics.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"30 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this computational study, a novel borophene polymorph, Ogee-Borophene, characterized by irregular decagon-shaped hollows was reported. The structure involves a deviation from hexagonal configurations found in all other known borophene polymorphs. The decagon-shaped hollow is highly related to the anisotropy of the structure, which results in three types of boron atoms with different electronic properties in the structure. In the study, the electronic structure and density of states of this novel structure were investigated with the help of density functional theory calculations. The electronic structure of Ogee-Borophene shows Dirac cone formations near the Fermi level. The discovery of a novel borophene polymorph, Ogee-Borophene, with irregular-shaped hollows represents a different point of view in the 2D materials field. The unique electronic properties of this material suggest that Ogee-Borophene has the potential to be used in a variety of applications, including transistors, and selective sensor applications without the need for additional doping.
{"title":"Electronic Properties of a Novel Boron Polymorph: Ogee-Borophene","authors":"B. Sarikavak-Lisesivdin, S. B. Lisesivdin","doi":"10.1155/2023/9933049","DOIUrl":"https://doi.org/10.1155/2023/9933049","url":null,"abstract":"In this computational study, a novel borophene polymorph, Ogee-Borophene, characterized by irregular decagon-shaped hollows was reported. The structure involves a deviation from hexagonal configurations found in all other known borophene polymorphs. The decagon-shaped hollow is highly related to the anisotropy of the structure, which results in three types of boron atoms with different electronic properties in the structure. In the study, the electronic structure and density of states of this novel structure were investigated with the help of density functional theory calculations. The electronic structure of Ogee-Borophene shows Dirac cone formations near the Fermi level. The discovery of a novel borophene polymorph, Ogee-Borophene, with irregular-shaped hollows represents a different point of view in the 2D materials field. The unique electronic properties of this material suggest that Ogee-Borophene has the potential to be used in a variety of applications, including transistors, and selective sensor applications without the need for additional doping.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"26 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136234705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Throughout this work, the equations of variation of the isothermal bulk modulus, its first pressure derivative, and the volumetric thermal expansion coefficient as a function of pressure were derived based on the Birch–Murnaghan equation of state (B–M EOS). The bulk modulus and its first derivative at ambient temperature for nine elements were extracted by fitting the published experimental pressure–volume data to B–M EOS, and the results were compared with other published researches, and there was a good agreement. Moreover, those extracted values were used to study the variation of the isothermal bulk modulus, its first pressure derivative, and the isothermal coefficient of thermal expansion as a function of the applied hydrostatic pressure using the equations that were derived from this work.
{"title":"Variation of Bulk Modulus, Its First Pressure Derivative, and Thermal Expansion Coefficient with Applied High Hydrostatic Pressure","authors":"Manaf A. Mahammed, Hamsa B. Mohammed","doi":"10.1155/2023/9518475","DOIUrl":"https://doi.org/10.1155/2023/9518475","url":null,"abstract":"Throughout this work, the equations of variation of the isothermal bulk modulus, its first pressure derivative, and the volumetric thermal expansion coefficient as a function of pressure were derived based on the Birch–Murnaghan equation of state (B–M EOS). The bulk modulus and its first derivative at ambient temperature for nine elements were extracted by fitting the published experimental pressure–volume data to B–M EOS, and the results were compared with other published researches, and there was a good agreement. Moreover, those extracted values were used to study the variation of the isothermal bulk modulus, its first pressure derivative, and the isothermal coefficient of thermal expansion as a function of the applied hydrostatic pressure using the equations that were derived from this work.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135967922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dispersion characteristics of surface waves for transverse electric and magnetic polarization modes of photonic hypercrystals (PHC) are theoretically explored. PHC are composed of a dielectric and hyperbolic metamaterial (HMM) with thin layers of both metal and dielectric surface waves that decay inside red-shifted gaps have a negative group velocity, whereas surface waves that decay inside traditional blue-shifted gaps have more typical characteristics. Curve plotting is used to elucidate on how these surface waves depend on several other structural properties such as filling factor, widths of HMM and dielectric, frequency range and angle of incidence etc.
{"title":"Dispersion Properties of Surface Waves Decaying in Red-Shifted and Blue-Shifted Gaps in Photonic Hypercrystals","authors":"Hasnain Haider, Munazza Zulfiqar Ali","doi":"10.1155/2023/6773192","DOIUrl":"https://doi.org/10.1155/2023/6773192","url":null,"abstract":"The dispersion characteristics of surface waves for transverse electric and magnetic polarization modes of photonic hypercrystals (PHC) are theoretically explored. PHC are composed of a dielectric and hyperbolic metamaterial (HMM) with thin layers of both metal and dielectric surface waves that decay inside red-shifted gaps have a negative group velocity, whereas surface waves that decay inside traditional blue-shifted gaps have more typical characteristics. Curve plotting is used to elucidate on how these surface waves depend on several other structural properties such as filling factor, widths of HMM and dielectric, frequency range and angle of incidence etc.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135253100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Perpetua Jelimo Chemaoi, Philip Otieno Nyawere, Christopher Mkirema Maghanga
Hybrid halide perovskites are promising photovoltaic materials for use in solar cells. The ongoing research on perovskites have shown that these materials are potential light-harvesting mediums. The optical properties of dimethylammonium triiodostanate (II) (DASnI3) a hybrid halide perovskites needs to be studied because it can be a good light absorber material due to the wide band gap exhibited. The real and the imaginary parts of the dielectric is a measure of the extent of light absorption. The GGA+U exchange-correlation implemented in Quantum ESPRESSO was used basing on density functional theory to obtain the optical properties. The DASnI3 has a direct band gap of 2.7 eV with the real part of the dielectric diagram indicating that the maximum value of ε1 (ω) is in the visible range of (3.0–3.5 eV). High absorption peaks were also observed in the visible spectral region at energy of around (3.5–4.5 eV) with several weak peaks observed in the energy range of (4.5–14.0 eV). The band structure and the dielectric functions are important in the study of optical properties. These properties expresses the interaction of light with the material medium and thus the luminescence of the device which are important in the use of DASnI3 as a solar cell material in photovoltaics.
{"title":"Computation of the Dielectric and Optical Properties of Dimethylammonium Tin Triiodostanate (II) Perovskite for Solar Cell Application","authors":"Perpetua Jelimo Chemaoi, Philip Otieno Nyawere, Christopher Mkirema Maghanga","doi":"10.1155/2023/2902298","DOIUrl":"https://doi.org/10.1155/2023/2902298","url":null,"abstract":"Hybrid halide perovskites are promising photovoltaic materials for use in solar cells. The ongoing research on perovskites have shown that these materials are potential light-harvesting mediums. The optical properties of dimethylammonium triiodostanate (II) (DASnI3) a hybrid halide perovskites needs to be studied because it can be a good light absorber material due to the wide band gap exhibited. The real and the imaginary parts of the dielectric is a measure of the extent of light absorption. The GGA+U exchange-correlation implemented in Quantum ESPRESSO was used basing on density functional theory to obtain the optical properties. The DASnI3 has a direct band gap of 2.7 eV with the real part of the dielectric diagram indicating that the maximum value of ε1 (ω) is in the visible range of (3.0–3.5 eV). High absorption peaks were also observed in the visible spectral region at energy of around (3.5–4.5 eV) with several weak peaks observed in the energy range of (4.5–14.0 eV). The band structure and the dielectric functions are important in the study of optical properties. These properties expresses the interaction of light with the material medium and thus the luminescence of the device which are important in the use of DASnI3 as a solar cell material in photovoltaics.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135345141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The main focus of this article is to investigate the theoretical interplay of magnetism and superconductivity in a two-band model for the iron-based superconductor Ba1−xKxFe2As2. On the basis of experimental results, the two-band model Hamiltonian was considered. We obtained mathematical statements for the superconductor Ba1−xKxFe2As2 superconducting (SC) transition temperature, spin-density-wave (SDW), transition temperature, superconductivity order parameter, and SDW order parameter from the Bogoliubov transformation formalism and the model Hamiltonian. Furthermore, an expression for the dependence of the SDW transition temperature on the SDW order parameter and the dependence of the SC transition temperature on the SDW order parameter was obtained for Ba1−xKxFe2As2. By substituting the experimental and theoretical values of the parameters in the derived statements, phase diagrams of the SC transition temperature versus the SDW order parameter and the SDW transition temperature versus the SDW order parameters have been plotted to demonstrate the dependence of the SDW order parameter on transition temperatures. By combining the two-phase diagrams, we depicted the possible coexistence of superconductivity and magnetism for the Ba1−xKxFe2As2 superconductor. The phase diagrams of temperature versus SC order parameter and temperature versus SDW order parameter were also plotted to show the dependence of order parameters on temperature for the Ba1−xKxFe2As2 superconductor.
{"title":"Theoretical Investigation of the Interplay of Superconductivity and Magnetism in Ba1−xKxFe2As2 Superconductor in a Two-Band Model by Using the Bogoliubov Transformation Formalism","authors":"Gedefaw Mebratie, Tigabu Bekele","doi":"10.1155/2023/9556764","DOIUrl":"https://doi.org/10.1155/2023/9556764","url":null,"abstract":"The main focus of this article is to investigate the theoretical interplay of magnetism and superconductivity in a two-band model for the iron-based superconductor Ba1−xKxFe2As2. On the basis of experimental results, the two-band model Hamiltonian was considered. We obtained mathematical statements for the superconductor Ba1−xKxFe2As2 superconducting (SC) transition temperature, spin-density-wave (SDW), transition temperature, superconductivity order parameter, and SDW order parameter from the Bogoliubov transformation formalism and the model Hamiltonian. Furthermore, an expression for the dependence of the SDW transition temperature on the SDW order parameter and the dependence of the SC transition temperature on the SDW order parameter was obtained for Ba1−xKxFe2As2. By substituting the experimental and theoretical values of the parameters in the derived statements, phase diagrams of the SC transition temperature versus the SDW order parameter and the SDW transition temperature versus the SDW order parameters have been plotted to demonstrate the dependence of the SDW order parameter on transition temperatures. By combining the two-phase diagrams, we depicted the possible coexistence of superconductivity and magnetism for the Ba1−xKxFe2As2 superconductor. The phase diagrams of temperature versus SC order parameter and temperature versus SDW order parameter were also plotted to show the dependence of order parameters on temperature for the Ba1−xKxFe2As2 superconductor.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"52 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75359285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Using the Green’s function method, we study the modulation of the conductance in zigzag graphene nanoribbon (ZGNR) junctions by the gate voltages. As long as the difference between the gate voltages applied on the left and right ZGNRs (ΔV) remains unchanged, the conductance profiles for different cases are exactly the same, except to a displacement along EF-axis. It is found that the transmission of electrons from the upper/lower edge state of the left ZGNR to the lower/upper edge state of the right ZGNR is forbidden, therefore, the width of the conductance gap increases first and then decreases as |ΔV| increases. The upper/lower edge states and conduction/valence subbands of ZGNR under higher/lower gate voltage (VH/VL) determine step positions of the conductance when EF >VH/EF < VL. But when VL ≤ EF ≤ VH, the conductance profile is mainly determined by the upper and lower edge states, a few lowest conduction subbands/topmost valence subbands of ZGNR under lower/higher gate voltage. These results are helpful to the exploration and application of a new kind of field effect transistor based on ZGNR junctions.
{"title":"Gate Voltage-Modulated Conductance in Zigzag Graphene Nanoribbon Junctions","authors":"Ming Li, Zhikang Feng, Zheng-Yin Zhao","doi":"10.1155/2023/6463744","DOIUrl":"https://doi.org/10.1155/2023/6463744","url":null,"abstract":"Using the Green’s function method, we study the modulation of the conductance in zigzag graphene nanoribbon (ZGNR) junctions by the gate voltages. As long as the difference between the gate voltages applied on the left and right ZGNRs (ΔV) remains unchanged, the conductance profiles for different cases are exactly the same, except to a displacement along EF-axis. It is found that the transmission of electrons from the upper/lower edge state of the left ZGNR to the lower/upper edge state of the right ZGNR is forbidden, therefore, the width of the conductance gap increases first and then decreases as |ΔV| increases. The upper/lower edge states and conduction/valence subbands of ZGNR under higher/lower gate voltage (VH/VL) determine step positions of the conductance when EF >VH/EF < VL. But when VL ≤ EF ≤ VH, the conductance profile is mainly determined by the upper and lower edge states, a few lowest conduction subbands/topmost valence subbands of ZGNR under lower/higher gate voltage. These results are helpful to the exploration and application of a new kind of field effect transistor based on ZGNR junctions.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"13 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73562243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigated the transport properties of diluted magnetic semiconductors (DMSs) theoretically by using the Heisenberg and Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange interaction models by considering both spin and charge disorder. The formalism is applied to the specific case of Ga 1 − x Mn x As . Using the Heisenberg model and the Green function formalism the total thermal excitation of the magnon is calculated. The magnetization and Curie temperature of Mn -doped GaAs is calculated. The theoretical calculation of T C of Ga 1 − x Mn x As at x = 0.08 has a good agreement with the experimental calculation at x = 0.08 (i.e., 162 k). The exchange interaction constant and spin-dependent relaxation time is calculated by using RKKY interaction. The electrical conductivity and hole mobility are calculated by using the Boltzmann transport equation and the spin-dependent relaxation time. The electrical conductivity of Mn -doped III–V DMS is exponentially increased with temperature and magnetic impurity concentration. Hole mobility of Mn -doped III–V diluted magnetic semiconductor is increased with the magnetic impurity concentration.
利用Heisenberg和Ruderman-Kittel-Kasuya-Yosida (RKKY)交换相互作用模型，在考虑自旋和电荷无序的情况下，从理论上研究了稀释磁性半导体(dms)的输运性质。该公式适用于Ga 1−x Mn x As的特殊情况。利用海森堡模型和格林函数形式，计算了磁振子的总热激发。计算了掺杂锰的砷化镓的磁化强度和居里温度。Ga 1−x Mn x As在x = 0.08时的理论计算结果与x = 0.08(即162 k)时的实验计算结果吻合较好。利用RKKY相互作用计算了交换相互作用常数和自旋相关的弛豫时间。利用玻尔兹曼输运方程和自旋相关弛豫时间计算了电导率和空穴迁移率。Mn掺杂的III-V DMS的电导率随温度和磁性杂质浓度呈指数增长。Mn掺杂的III-V稀释磁性半导体的空穴迁移率随磁性杂质浓度的增加而增加。
{"title":"The Study of Transport Properties of (III−Mn) V Diluted Magnetic Semiconductors","authors":"Edosa Tasisa Jira, H. Berry","doi":"10.1155/2023/8860586","DOIUrl":"https://doi.org/10.1155/2023/8860586","url":null,"abstract":"We investigated the transport properties of diluted magnetic semiconductors (DMSs) theoretically by using the Heisenberg and Ruderman–Kittel–Kasuya–Yosida (RKKY) exchange interaction models by considering both spin and charge disorder. The formalism is applied to the specific case of \u0000 \u0000 \u0000 Ga\u0000 \u0000 1\u0000 −\u0000 x\u0000 \u0000 \u0000 \u0000 Mn\u0000 \u0000 x\u0000 \u0000 \u0000 As\u0000 \u0000 . Using the Heisenberg model and the Green function formalism the total thermal excitation of the magnon is calculated. The magnetization and Curie temperature of \u0000 \u0000 Mn\u0000 \u0000 -doped \u0000 \u0000 GaAs\u0000 \u0000 is calculated. The theoretical calculation of \u0000 \u0000 \u0000 T\u0000 \u0000 C\u0000 \u0000 \u0000 \u0000 of \u0000 \u0000 \u0000 Ga\u0000 \u0000 1\u0000 −\u0000 x\u0000 \u0000 \u0000 \u0000 Mn\u0000 \u0000 x\u0000 \u0000 \u0000 As\u0000 \u0000 at x = 0.08 has a good agreement with the experimental calculation at x = 0.08 (i.e., 162 k). The exchange interaction constant and spin-dependent relaxation time is calculated by using RKKY interaction. The electrical conductivity and hole mobility are calculated by using the Boltzmann transport equation and the spin-dependent relaxation time. The electrical conductivity of \u0000 \u0000 Mn\u0000 \u0000 -doped III–V DMS is exponentially increased with temperature and magnetic impurity concentration. Hole mobility of \u0000 \u0000 Mn\u0000 \u0000 -doped III–V diluted magnetic semiconductor is increased with the magnetic impurity concentration.","PeriodicalId":7382,"journal":{"name":"Advances in Condensed Matter Physics","volume":"52 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88989315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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