scholarly journals Tunneling effect in gapped graphene disk in magnetic flux and electrostatic potential

2021 ◽  
Author(s):  
A. Babe Cheikh ◽  
A. Bouhlal ◽  
Ahmed Jellal ◽  
E. H. Atmani
Keyword(s):  
Magnetic Flux ◽  
Electrostatic Potential ◽  
Energy Gap ◽  
Fano Factor ◽  
Mass Term ◽  
Tunneling Effect ◽  
Gapped Graphene ◽  
Klein Tunneling ◽  
Hankel Functions ◽  
Corbino Disk

Abstract We investigate the tunneling effect of a Corbino disk in graphene in the presence of a variable magnetic flux Φi created by a solenoid piercing the inner disk under the effect of a finite mass term in the disk region (R1 < r < R2) and an electrostatic potential. Considering different regions, we explicitly determine the associated eigenspinors in terms of Hankel functions. The use of matching conditions and asymptotic behavior of Hankel functions for large arguments, enables us to calculate transmission and other transport quantities. Our results show that the energy gap suppresses the tunneling effect by creating singularity points of zero transmission corresponding to the maximum shot noise peaks quantified by the Fano factor F . The transmission as a function of the radii ratio R2/R1 becomes oscillatory with a decrease in periods and amplitudes. It can even reach one (Klein tunneling) for large values of the energy gap. The appearance of the minimal conductance at the points kF R1 = R1δ is observed. Finally we find that the electrostatic potential can control the effect of the band gap.

Scattering in gapped graphene quantum dot with magnetic flux

2020 ◽  
Vol 95 (10) ◽  
pp. 105805
Author(s):  
Bouchaib Lemaalem ◽  
Abdelhadi Belouad ◽  
Miloud Mekkaoui ◽  
Ahmed Jellal
Keyword(s):  
Quantum Dot ◽  
Magnetic Flux ◽  
Gapped Graphene ◽  
Graphene Quantum Dot

scholarly journals Effects of A Magnetic Field on the Transport and Noise Properties of a Graphene Ribbon with Antidots

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2098
Author(s):  
Paolo Marconcini ◽  
Massimo Macucci
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Charge Transport ◽  
Shot Noise ◽  
Energy Gap ◽  
Mass Term ◽  
Edge States ◽  
Graphene Ribbon ◽  
The Magnetic Field ◽  
Armchair Graphene

We perform a numerical simulation of the effects of an orthogonal magnetic field on charge transport and shot noise in an armchair graphene ribbon with a lattice of antidots. This study relies on our envelope-function based code, in which the presence of antidots is simulated through a nonzero mass term and the magnetic field is introduced with a proper choice of gauge for the vector potential. We observe that by increasing the magnetic field, the energy gap present with no magnetic field progressively disappears, together with features related to commensurability and quantum effects. In particular, we focus on the behavior for high values of the magnetic field: we notice that when it is sufficiently large, the effect of the antidots vanishes and shot noise disappears, as a consequence of the formation of edge states crawling along the boundaries of the structure without experiencing any interaction with the antidots.

scholarly journals Electrostatic Design of Polar Metal–Organic Framework Thin Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2420
Author(s):  
Giulia Nascimbeni ◽  
Christof Wöll ◽  
Egbert Zojer
Keyword(s):  
Thin Films ◽  
Electrostatic Potential ◽  
Energy Gap ◽  
Dipole Moments ◽  
Metal Organic Framework ◽  
Solid Substrate ◽  
Layer Growth ◽  
Layer By Layer ◽  
Metal Organic ◽  
Linker Molecules

In recent years, optical and electronic properties of metal–organic frameworks (MOFs) have increasingly shifted into the focus of interest of the scientific community. Here, we discuss a strategy for conveniently tuning these properties through electrostatic design. More specifically, based on quantum-mechanical simulations, we suggest an approach for creating a gradient of the electrostatic potential within a MOF thin film, exploiting collective electrostatic effects. With a suitable orientation of polar apical linkers, the resulting non-centrosymmetric packing results in an energy staircase of the frontier electronic states reminiscent of the situation in a pin-photodiode. The observed one dimensional gradient of the electrostatic potential causes a closure of the global energy gap and also shifts core-level energies by an amount equaling the size of the original band gap. The realization of such assemblies could be based on so-called pillared layer MOFs fabricated in an oriented fashion on a solid substrate employing layer by layer growth techniques. In this context, the simulations provide guidelines regarding the design of the polar apical linker molecules that would allow the realization of MOF thin films with the (vast majority of the) molecular dipole moments pointing in the same direction.

scholarly journals Crystal structure and DFT study of a zinc xanthate complex

2019 ◽  
Vol 75 (11) ◽  
pp. 1582-1585 ◽  
Author(s):  
Adnan M. Qadir ◽  
Sevgi Kansiz ◽  
Necmi Dege ◽  
Georgina M. Rosair ◽  
Igor O. Fritsky
Keyword(s):  
Molecular Structure ◽  
Electrostatic Potential ◽  
Density Functional ◽  
Molecular Electrostatic Potential ◽  
Energy Gap ◽  
Three Dimensional ◽  
Intramolecular Interactions ◽  
Lumo Energy ◽  
Functional Theory ◽  
Homo Lumo

In the title compound, bis(2-methoxyethyl xanthato-κS)(N,N,N′,N′-tetramethylethylenediamine-κ2 N,N′)zinc(II) acetone hemisolvate, [Zn(C4H7O2S2)2(C6H16N2)]·0.5C3H6O, the ZnII ion is coordinated by two N atoms of the N,N,N′,N′-tetramethylethylenediamine ligand and two S atoms from two 2-methoxyethyl xanthate ligands. The amine ligand is disordered over two orientations and was modelled with refined occupancies of 0.538 (6) and 0.462 (6). The molecular structure features two C—H...O and two C—H...S intramolecular interactions. In the crystal, molecules are linked by weak C—H...O and C—H...S hydrogen bonds, forming a three-dimensional supramolecular architecture. The molecular structure was optimized using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level. The smallest HOMO–LUMO energy gap (3.19 eV) indicates the suitability of this crystal for optoelectronic applications. The molecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the molecules. Half a molecule of disordered acetone was removed with the solvent-mask procedure in OLEX2 [Dolomanov et al. (2009). J. Appl. Cryst. 42, 339–341] and this contribition is included in the formula.

scholarly journals Molecular Structure, Spectral Investigations, Hydrogen Bonding Interactions and Reactivity-Property Relationship of Caffeine-Citric Acid Cocrystal by Experimental and DFT Approach

2021 ◽  
Vol 9 ◽  
Author(s):  
Priya Verma ◽  
Anubha Srivastava ◽  
Karnica Srivastava ◽  
Poonam Tandon ◽  
Manishkumar R. Shimpi
Keyword(s):  
Hydrogen Bonding ◽  
Citric Acid ◽  
Electrostatic Potential ◽  
Energy Gap ◽  
Intermolecular Hydrogen Bond ◽  
Active Form ◽  
Intermolecular Hydrogen Bonding ◽  
Scanning Calorimetry ◽  
Property Relationship ◽  
Hydrogen Bonding Interactions

The pharmaceutical cocrystal of caffeine-citric acid (CAF-CA, Form II) has been studied to explore the presence of hydrogen bonding interactions and structure-reactivity-property relationship between the two constituents CAF and Citric acid. The cocrystal was prepared by slurry crystallization. Powder X-ray diffraction (PXRD) analysis was done to characterize CAF-CA cocrystal. Also, differential scanning calorimetry (DSC) confirmed the existence of CAF-CA cocrystal. The vibrational spectroscopic (FT-IR and FT-Raman) signatures and quantum chemical approach have been used as a strategy to get insights into structural and spectral features of CAF-CA cocrystal. There was a good correlation among the experimental and theoretical results of dimer of cocrystal, as this model is capable of covering all nearest possible interactions present in the crystal structure of cocrystal. The spectroscopic results confirmed that (O33-H34) mode forms an intramolecular (C25 = O28∙∙∙H34-O33), while (O26-H27) (O39-H40) and (O43-H44) groups form intermolecular hydrogen bonding (O26-H27∙∙∙N24-C22, O39-H40∙∙∙O52 = C51 and O43-H44∙∙∙O86 = C83) in cocrystal due to red shifting and increment in bond length. The quantum theory of atoms in molecules (QTAIM) analysis revealed (O88-H89∙∙∙O41) as strongest intermolecular hydrogen bonding interaction with interaction energy −12.4247 kcal mol−1 in CAF-CA cocrystal. The natural bond orbital analysis of the second-order theory of the Fock matrix highlighted the presence of strong interactions (N∙∙∙H and O∙∙∙H) in cocrystal. The HOMO-LUMO energy gap value shows that the CAF-CA cocrystal is more reactive, less stable and softer than CAF active pharmaceutical ingredients. The electrophilic and nucleophilic reactivities of atomic sites involved in intermolecular hydrogen bond interactions in cocrystal have been demonstrated by mapping electron density isosurfaces over electrostatic potential i.e. plotting molecular electrostatic potential (MESP) map. The molar refractivity value of cocrystal lies within the set range by Lipinski and hence it may be used as orally active form. The results show that the physicochemical properties of CAF-CA cocrystal are enhanced in comparison to CAF (API).

Giant Fano factor and bistability in a Corbino disk in the quantum Hall effect breakdown regime

2016 ◽  
Vol 28 (5) ◽  
pp. 055801 ◽  
Author(s):  
Tokuro Hata ◽  
Tomonori Arakawa ◽  
Kensaku Chida ◽  
Sadashige Matsuo ◽  
Kensuke Kobayashi
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Fano Factor ◽  
Corbino Disk

scholarly journals NONUNIVERSAL TUNNELING RESISTANCE AT THE QUANTUM CRITICAL POINT OF MESOSCOPIC SQUIDS ARRAY

2012 ◽  
Vol 26 (15) ◽  
pp. 1250099
Author(s):  
SUJIT SARKAR
Keyword(s):  
Magnetic Flux ◽  
Critical Point ◽  
Quantum Critical Point ◽  
Luttinger Liquid ◽  
Tunneling Effect ◽  
Analytical Relation ◽  
Metallic State ◽  
Quantum Critical ◽  
Liquid Parameter ◽  
Tunneling Resistance

We calculate the tunneling resistance at the quantum critical point of a mesoscopic SQUIDs array in the presence of magnetic flux. We observe nonuniversal bahaviour of tunneling resistance. We find the analytical relation between the magnetic flux induced dissipation strength and the Luttinger liquid parameter of the system. We also predict the evidence of length scale independent metallic state. This study also emphasizes the importance of co-tunneling effect.

Sign in / Sign up

Export Citation Format

Share Document