scholarly journals Development of a ferromagnetic component in the superconducting state of Fe-excess Fe1.12Te1-xSex by electronic charge redistribution

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Wen-Hsien Li ◽  
Sunil K. Karna ◽  
Han Hsu ◽  
Chi-Yen Li ◽  
Chi-Hung Lee ◽  
...  
Keyword(s):  
Superconducting State ◽  
Electronic Charge ◽  
Charge Redistribution ◽  
Ferromagnetic Component ◽  
Fe Excess

scholarly journals Chirality-induced spin polarization places symmetry constraints on biomolecular interactions

2017 ◽  
Vol 114 (10) ◽  
pp. 2474-2478 ◽  
Author(s):  
Anup Kumar ◽  
Eyal Capua ◽  
Manoj K. Kesharwani ◽  
Jan M. L. Martin ◽  
Einat Sitbon ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Noncovalent Interactions ◽  
Electronic Charge ◽  
Biological Processes ◽  
Interaction Energies ◽  
Hall Voltage ◽  
Charge Redistribution ◽  
Chiral Molecules ◽  
Quantum Chemistry Calculations ◽  
Symmetry Constraints

Noncovalent interactions between molecules are key for many biological processes. Necessarily, when molecules interact, the electronic charge in each of them is redistributed. Here, we show experimentally that, in chiral molecules, charge redistribution is accompanied by spin polarization. We describe how this spin polarization adds an enantioselective term to the forces, so that homochiral interaction energies differ from heterochiral ones. The spin polarization was measured by using a modified Hall effect device. An electric field that is applied along the molecules causes charge redistribution, and for chiral molecules, a Hall voltage is measured that indicates the spin polarization. Based on this observation, we conjecture that the spin polarization enforces symmetry constraints on the biorecognition process between two chiral molecules, and we describe how these constraints can lead to selectivity in the interaction between enantiomers based on their handedness. Model quantum chemistry calculations that rigorously enforce these constraints show that the interaction energy for methyl groups on homochiral molecules differs significantly from that found for heterochiral molecules at van der Waals contact and shorter (i.e., ∼0.5 kcal/mol at 0.26 nm).

Fe-excess Ions as Electronic Charge Suppliers for Zero Thermal Expansion in the Normal State of Fe1.16Te0.6Se0.4

2015 ◽  
Vol 84 (9) ◽  
pp. 094713
Author(s):  
Sunil K. Karna ◽  
Chi-Hung Lee ◽  
Wen-Hsien Li ◽  
Raman Sankar ◽  
Fang-Cheng Chou ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Normal State ◽  
Electronic Charge ◽  
Fe Excess

scholarly journals Ab-Initio Calculations of Oxygen Vacancy in Ga2O3 Crystals

2021 ◽  
Vol 58 (2) ◽  
pp. 3-10
Author(s):  
A. Usseinov ◽  
Zh. Koishybayeva ◽  
A. Platonenko ◽  
A. Akilbekov ◽  
J. Purans ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Gallium Oxide ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Wide Band ◽  
Electronic Charge ◽  
Charge Redistribution ◽  
Wide Band Gap ◽  
Exchange Correlation ◽  
Deep Donor

Abstract Gallium oxide β-Ga2O3 is an important wide-band gap semiconductor. In this study, we have calculated the formation energy and transition levels of oxygen vacancies in β-Ga2O3 crystal using the B3LYP hybrid exchange-correlation functional within the LCAO-DFT approach. The obtained electronic charge redistribution in perfect Ga2O3 shows notable covalency of the Ga-O bonds. The formation of the neutral oxygen vacancy in β-Ga2O3 leads to the presence of deep donor defects with quite low concentration. This is a clear reason why oxygen vacancies can be hardly responsible for n-type conductivity in β-Ga2O3.

scholarly journals Development of Ferromagnetic Superspins in Bare Cu Nanoparticles by Electronic Charge Redistribution

2015 ◽  
Vol 16 (10) ◽  
pp. 23165-23176 ◽  
Author(s):  
Erdembayalag Batsaikhan ◽  
Yen-Cheng Chen ◽  
Chi-Hung Lee ◽  
Hsiao-Chi Li ◽  
Wen-Hsien Li
Keyword(s):  
Electronic Charge ◽  
Cu Nanoparticles ◽  
Charge Redistribution

Grain Boundary Chemistry and Ductility in Ni-Base LI2 Intermetallic Compounds

1986 ◽  
Vol 81 ◽  
Author(s):  
A. I. Taub ◽  
C. L. Briant
Keyword(s):  
Experimental Data ◽  
Intergranular Fracture ◽  
The Other ◽  
Electronic Charge ◽  
Charge Redistribution ◽  
Brittle Behavior ◽  
Charge Localization ◽  
Binary Compounds ◽  
Boundary Chemistry ◽  
Brittle Intergranular Fracture

AbstractThe available experimental data for the Ni3X, LI2 intermetallics indicate a strong effect of chemistry on the tendency for brittle intergranular fracture. Combining the data for the binary compounds with the effects of macroalloying with × substituents and microalloying with boron, the resistance to intergranular fracture varies as Fe ~ Mn > Al ~ Ga > Si > Ge. Two models have been proposed to explain these chemistry effects. The basis for both models is that electronic charge localization is responsible for the brittle behavior of the ordered intermetallics. The models differ in the measure of charge redistribution; one uses valency differences whereas the other uses electronegativity differences.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

Relation Between Local Structure, Electric Dipole and Charge Carrier Dynamics in DHICA Melanin, a Model for Biocompatible Semiconductors

2019 ◽  
Author(s):  
Micaela Matta ◽  
Alessandro Pezzella ◽  
Alessandro Troisi
Keyword(s):  
Electronic Structure ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Computational Study ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Polymer Semiconductors ◽  
Synthetic Pigments

<div><div><div><p>Eumelanins are a family of natural and synthetic pigments obtained by oxidative polymerization of their natural precursors: 5,6 dihydroxyindole and its 2-carboxy derivative (DHICA). The simultaneous presence of ionic and electronic charge carriers makes these pigments promising materials for applications in bioelectronics. In this computational study we build a structural model of DHICA melanin considering the interplay between its many degrees of freedom, then we examine the electronic structure of representative oligomers. We find that a non-vanishing dipole along the polymer chain sets this system apart from conventional polymer semiconductors, determining its electronic structure, reactivity toward oxidation and localization of the charge carriers. Our work sheds light on previously unnoticed features of DHICA melanin that not only fit well with its radical scavenging and photoprotective properties, but open new perspectives towards understanding and tuning charge transport in this class of materials.<br></p></div></div></div>

Field Effect Modulation of Electrocatalytic Hydrogen Evolution at Back-Gated Two-Dimensional MoS2 Electrodes

2019 ◽  
Author(s):  
Yan Wang ◽  
Sagar Udyavara ◽  
Matthew Neurock ◽  
C. Daniel Frisbie
Keyword(s):  
Electric Field ◽  
Hydrogen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Electrode Materials ◽  
Density Functional Theory Calculations ◽  
Electronic Charge ◽  
Back Side ◽  
Gate Electrode ◽  
Conventional Manner

<div> <div> <div> <p> </p><div> <div> <div> <p>Electrocatalytic activity for hydrogen evolution at monolayer MoS2 electrodes can be enhanced by the application of an electric field normal to the electrode plane. The electric field is produced by a gate electrode lying underneath the MoS2 and separated from it by a dielectric. Application of a voltage to the back-side gate electrode while sweeping the MoS2 electrochemical potential in a conventional manner in 0.5 M H2SO4 results in up to a 140-mV reduction in overpotential for hydrogen evolution at current densities of 50 mA/cm2. Tafel analysis indicates that the exchange current density is correspondingly improved by a factor of 4 to 0.1 mA/cm2 as gate voltage is increased. Density functional theory calculations support a mechanism in which the higher hydrogen evolution activity is caused by gate-induced electronic charge on Mo metal centers adjacent the S vacancies (the active sites), leading to enhanced Mo-H bond strengths. Overall, our findings indicate that the back-gated working electrode architecture is a convenient and versatile platform for investigating the connection between tunable electronic charge at active sites and overpotential for electrocatalytic processes on ultrathin electrode materials.</p></div></div></div><br><p></p></div></div></div>

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