Electromagnetic metamaterial with built-in microstructures

Li, Jensen; Chan, Che Ting

doi:10.1103/physrevb.72.195103

Cited by 9 publications

(9 citation statements)

References 28 publications

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“…(3) and solve the Hamiltonian H self consistently as in a traditional ABMD to get H(t). Here we will use the charge patching method (CPM) [34,34] to get ρ 0 (t) for a given atomic configuration {R(t)}. The CPM [34,35] is a well tested method to provide the ground state electronic charge density without going through a self consistent calculation.…”

Section: The Formalism and The Approximationsmentioning

confidence: 99%

“…Here we will use the charge patching method (CPM) [34,34] to get ρ 0 (t) for a given atomic configuration {R(t)}. The CPM [34,35] is a well tested method to provide the ground state electronic charge density without going through a self consistent calculation. It generates atomic charge density motifs from small system calculations, then patches these motifs together to get the charge density of a large system.…”

Section: The Formalism and The Approximationsmentioning

confidence: 99%

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Nonadiabatic molecular dynamics simulation for carrier transport in a pentathiophene butyric acid monolayer

2013

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We present a new approach to carry out non-adiabatic molecular dynamics to study the carrier mobility in an organic monolayer. This approach allows the calculation of a 4802 atom system for 825 fs in about three hours using 51,744 computer cores while maintaining a plane wave pseudopotential density functional theory level accuracy for the Hamiltonian. Our simulation on a pentathiophene butyric acid monolayer reveals a previously unknown new mechanism for the carrier transport in such systems: the hole wave functions are localized by thermo fluctuation induced disorder, while its transport is via charge transfer during state energy crossing. The simulation also shows that the system is not in thermo dynamic equilibrium in terms of adiabatic state populations according to Boltzmann distribution. Our simulation is achieved by introducing a linear time dependence approximation of the Hamiltonian within a fs time interval, and by using the charge patching method to yield the Hamiltonian, and overlapping fragment method to diagonalize the Hamiltonian matrix.

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Section: The Formalism and The Approximationsmentioning

confidence: 99%

Section: The Formalism and The Approximationsmentioning

confidence: 99%

Nonadiabatic molecular dynamics simulation for carrier transport in a pentathiophene butyric acid monolayer

2013

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“…The symmetry energy for nuclear matter E sym is very important for understanding not only the structure of nuclei far from β stability line, the dynamics and many interesting phenomena in reactions of isospin asymmetric nuclei but also many critical issues in astrophysics [1]. Recent research on the symmetry energy for cold nuclear matter has already obtained a great progress and some constraints on the density dependence of the symmetry energy at subnormal densities have been set [2,3,4,5,6]. But the density dependence of the symmetry energy at high densities extracted from the ratio of π − /π + and other observables in heavy ion collisions at intermediate high energies are extremely model dependent and divergent [7,8].…”

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confidence: 99%

Effect of the splitting of the neutron and proton effective masses on the nuclear symmetry energy at finite temperatures

Zhang

et al. 2011

Physics Letters B

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We present the temperature and density dependence of symmetry energy for nuclear matter at finite temperature based on the approach of the thermodynamics with Skyrme energy density functional. We first classify the Skyrme interactions into 7 groups according to the range of neutron and proton effective mass in neutron matter limit(99.99 per cent neutron in the matter). We find that there is obvious correlation between the temperature dependence of the symmetry energy and the splitting of the neutron and proton effective mass. For some Skyrme interactions with m * n > m * p and strong splitting of the neutron and proton effective mass in asymmetric nuclear matter, a transition of the temperature dependence of symmetry energy from decreasing with temperature at low densities to increasing with temperature at high densities appears. For other Skyrme interactions, we do not observe such phenomenon. Our study show that the symmetry energy in hot asymmetric matter not only depends on symmetry potential part but also on the splitting of the neutron and proton effective mass to a certain extent.Keywords: nuclear symmetry energy, nuclear symmetry energy at finite temperature, Skyrme density functional, Splitting of neutron and proton effective mass

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“…The novel materials appeared remarkably interesting and revealed a number of unusual properties not yet well understood. Huge positive magnetoresistance of hundreds to thousands of percent [1][2][3][4], reversal of magnetoresistance from positive to negative after annealing [4], and large Hall effect with non-monotonic field dependence [5][6][7] are among them. Interpretation of the data is difficult owing to the complicated structure of these alloys.…”

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confidence: 99%

Magnetization-driven metal-insulator transition in strongly disordered Ge:Mn magnetic semiconductors

et al. 2009

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We report on the temperature-and field-driven metal-insulator transition in disordered Ge:Mn magnetic semiconductors accompanied by magnetic ordering, magnetoresistance reaching thousands of percents, and suppression of the extraordinary Hall effect by a magnetic field. Magnetoresistance isotherms are shown to obey a universal scaling law with a single scaling parameter depending on temperature and fabrication. We argue that the strong magnetic disorder leads to localization of charge carriers and is the origin of the unusual properties of Ge:Mn alloys.Interest in magnetic semiconductors was triggered by the development of spintronics in metallic magnetic materials and prospects to empower the semiconducting electronics by the spin-dependent degree of freedom. Compatibility with the existing silicon technology recently attracted much attention to the group-IV semiconductors doped with magnetic impurities. The novel materials appeared remarkably interesting and revealed a number of unusual properties not yet well understood. Huge positive magnetoresistance ͑MR͒ of hundreds to thousands of percent, 1-4 reversal of magnetoresistance from positive to negative after annealing, 4 and large Hall effect with nonmonotonic field dependence 5-7 are among them. Interpretation of the data is difficult owing to the complicated structure of these alloys. As a result, almost no general relations were derived from the experiments, and only special models were proposed to explain the data in each case.In this Rapid Communication we report on the high-field magnetic and magnetotransport properties of several Ge:Mn samples produced by ion implantation. The material was found to pass from metallic-like to insulator-like state, either at low temperatures in zero field or under an applied field at elevated temperatures. We show that all the magnetoresistance data can be scaled on a universal curve with a single parameter H s , which tends to zero at the paramagnet-toferromagnet transition. The same scaling procedure is applicable to the published data 4 obtained in samples produced by the molecular-beam epitaxy, which indicates the generality of the scaling approach. We argue that establishment of an inhomogeneous magnetization landscape leads to localization of the charge carriers and, respectively, to a huge positive magnetoresistance and a total suppression of the extraordinary Hall effect.Two Ge:Mn samples discussed here were fabricated by implanting Mn + ions into commercial single-crystalline Ge͑100͒ wafers with resistivity of 40-57 ⍀ cm. Mn + ions were implanted with an energy of 100 keV at fluences of 1 ϫ 10 16 and 2 ϫ 10 16 that produce average volume concentrations of Mn of about 2 and 4 at. % in the projected depth range of about 120 nm. During the implantation, the samples were held at 300°C to avoid amorphization. Structure of the samples is strongly nonuniform, depending on the concentration, and contains diluted Mn, amorphous semiconducting Mn-rich nanoclusters, and ferromagnetic metallic Mn 5 Ge 3 clusters. Detailed str...

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Electromagnetic metamaterial with built-in microstructures

Cited by 9 publications

References 28 publications

Nonadiabatic molecular dynamics simulation for carrier transport in a pentathiophene butyric acid monolayer

Nonadiabatic molecular dynamics simulation for carrier transport in a pentathiophene butyric acid monolayer

Effect of the splitting of the neutron and proton effective masses on the nuclear symmetry energy at finite temperatures

Magnetization-driven metal-insulator transition in strongly disordered Ge:Mn magnetic semiconductors

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