| 1. |
- Chen, X, et al.
(författare)
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Bismuth Effects on Electronic Levels in GaSb(Bi)/AlGaSb Quantum Wells Probed by Infrared Photoreflectance
- 2015
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 32:6
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Tidskriftsartikel (refereegranskat)abstract
- GaSb(Bi)/Al0.2Ga0.8Sb single quantum wells are characterized by a Fourier transform infrared spectrometerbased photoreflectance method at 77 K. Spatially direct and indirect transitions between the electronic levels at and above the effective band gap are well resolved. The shifts of the electronic levels with Bi incorporation are identified quantitatively. The results show that the upshift of the valence band edge is clarified to be dominant, while the Bi-induced downshift of the conduction band edge does exist and contributes to the band gap reduction in the GaSbBi quantum-well layer by (29±6)%.
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| 2. |
- Dong, Yu, et al.
(författare)
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Observation of a Ubiquitous (π, π)-Type Nematic Superconducting Order in the Whole Superconducting Dome of Ultra-Thin BaFe2–xNixAs2 Single Crystals
- 2021
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Ingår i: Chinese Physics Letters. - : Institute of Physics Publishing (IOPP). - 0256-307X .- 1741-3540. ; 38:9
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Tidskriftsartikel (refereegranskat)abstract
- In iron-based superconductors, the (0, pi) or (pi, 0) nematicity, which describes an electronic anisotropy with a four-fold symmetry breaking, is well established and believed to be important for understanding the superconducting mechanism. However, how exactly such a nematic order observed in the normal state can be related to the superconducting pairing is still elusive. Here, by performing angular-dependent in-plane magnetoresistivity using ultra-thin flakes in the steep superconducting transition region, we unveil a nematic superconducting order along the (pi, pi) direction in electron-doped BaFe2 - x Ni x As2 from under-doped to heavily overdoped regimes with x = 0.065-0.18. It shows superconducting gap maxima along the (pi, pi) direction rotated by 45 degrees from the nematicity along (0, pi) or (pi, 0) direction observed in the normal state. A similar (pi, pi)-type nematicity is also observed in the under-doped and optimally doped hole-type Ba1 - y K y Fe2As2, with y = 0.2-0.5. These results suggest that the (pi, pi) nematic superconducting order is a universal feature that needs to be taken into account in the superconducting pairing mechanism in iron-based superconductors.
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| 3. |
- Guang-Jun, Tian, et al.
(författare)
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Two Possible Configurations for Silver-C-60-Silver Molecular Devices and Their Conductance Characteristics
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:6, s. 068501-
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Tidskriftsartikel (refereegranskat)abstract
- Coherent electronic transport properties of silver-C-60-silver molecular junctions in different configurations are studied using hybrid density function theory. The experimentally measured current flows of C-60 molecules adsorbed on the silver surface are well reproduced by theoretical calculations. It is found that the current-voltage characteristics of the molecular junctions depend strongly on the configurations of the junctions. Transmission spectra combined with density of states can help us to understand in depth the transport properties. Different kinds of electrode construction are also discussed. With the help of the calculation, two possible configurations of silver-C-60-silver molecular junctions are suggested.
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| 4. |
- Hamzavi, M., et al.
(författare)
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Approximate analytical solution of the yukawa potential with arbitrary angular momenta
- 2012
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 29:8, s. 080302-
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Tidskriftsartikel (refereegranskat)abstract
- The Yukawa potential is often used to compute bound-state normalizations and energy levels of neutral atoms. By using the generalized parametric Nikiforov-Uvarov method, we obtain approximate analytical solutions of the radial Schrödinger equation for the Yukawa potential. The energy eigenvalues and the corresponding eigenfunctions are calculated in closed forms. Some numerical results are presented and show that these results are in good agreement with those obtained previously by other methods. Also, we find the energy levels of the familiar pure Coulomb potential energy levels when the screening parameter of the Yukawa potential goes to zero.
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| 5. |
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| 6. |
- Huang, Yue, et al.
(författare)
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Memory Effect of Metal-Oxide-Silicon Capacitors with Self-Assembly Double-Layer Au Nanocrystals Embedded in Atomic-Layer-Deposited HfO2 Dielectric
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- We report the chemical self-assembly growth of Au nanocrystals on atomic-layer-deposited HfO2 films aminosilanized by (3-Aminopropyl)-trimethoxysilane aforehand for memory applications. The resulting Au nanocrystals show a density of about 4 x 10(11) cm(-2) and a diameter range of 5-8 nm. The metal-oxide-silicon capacitor with double-layer Au nanocrystals embedded in HfO2 dielectric exhibits a large C - V hysteresis window of 11.9 V for +/- 11 V gate voltage sweeps at 1 MHz, a flat-band voltage shift of 1.5 V after the electrical stress under 7 V for 1 ms, a leakage current density of 2.9 x 10(-8) A/cm(-2) at 9 V and room temperature. Compared to single-layer Au nanocrystals, the double-layer Au nanocrystals increase the hysteresis window significantly, and the underlying mechanism is thus discussed.
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| 7. |
- Liao, Zhong-Wei, et al.
(författare)
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Robust Low Voltage Program-Erasable Cobalt-Nanocrystal Memory Capacitors with Multistacked Al2O3/HfO2/Al2O3 Tunnel Barrier
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:8, s. 087303-
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Tidskriftsartikel (refereegranskat)abstract
- An atomic-layer-deposited Al2O3/HfO2/Al2O3 (A/H/A) tunnel barrier is investigated for Co nanocrystal memory capacitors. Compared to a single Al2O3 tunnel barrier, the A/H/A barrier can significantly increase the hysteresis window, i. e., an increase by 9V for +/- 12V sweep range. This is attributed to a marked decrease in the energy barriers of charge injections for the A/H/A tunnel barrier. Further, the Co-nanocrystal memory capacitor with the A/H/A tunnel barrier exhibits a memory window as large as 4.1V for 100 mu s program/erase at a low voltage of +/- 7V, which is due to fast charge injection rates, i. e., about 2.4 x 10(16) cm(-2) s(-1) for electrons and 1.9 x 10(16) cm(-2) s(-1) for holes.
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| 8. |
- Song, Jiao-Jiao, et al.
(författare)
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The 4f-Hybridization Strength in CemMnIn3m+2n Heavy-Fermion Compounds Studied by Angle-Resolved Photoemission Spectroscopy
- 2021
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Ingår i: Chinese Physics Letters. - : IOP Publishing. - 0256-307X .- 1741-3540. ; 38:10
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Tidskriftsartikel (refereegranskat)abstract
- We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds CemMnIn3m+2n (with M = Co, Rh, Jr, and Pt, m = 1, 2, n = 0-2), at low temperature using on-resonance angle-resolved photoemission spectroscopy. Three heavy quasiparticle bands f(0), f(7/2)(1) and f(5/2)(1), are observed in all compounds, whereas their intensities and energy locations vary greatly with materials. The strong f(0) states imply that the localized electron behavior dominates the Ce 4f states. The Ce 4f electrons are partially hybridized with the conduction electrons, making them have the dual nature of localization and itinerancy. Our quantitative comparison reveals that the f(5/2)(1)-f (0) intensity ratio is more suitable to reflect the 4f-state hybridization strength.
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| 9. |
- Wang, Chang, et al.
(författare)
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Band Structure and Optical Gain of InGaAs/GaAsBi Type-II Quantum Wells Modeled by the k center dot p Model
- 2018
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 35:5
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Tidskriftsartikel (refereegranskat)abstract
- Optical gains of type-II InGaAs/GaAsBi quantum wells (QWs) with W, N, and M shapes are analyzed theoretically for near-infrared laser applications. The bandgap and wave functions are calculated using the self-consistent k . p Hamiltonian, taking into account valence band mixing and the strain effect. Our calculations show that the M-shaped type-II QWs are a promising structure for making 1.3 mu m lasers at room temperature because they can easily be used to obtain 1.3 mu m for photoluminescence with a proper thickness and have large wave-function overlap for high optical gain.
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| 10. |
- Wang, G.Q., et al.
(författare)
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Excitation of Zonal Flows by Ion temperature gradient Modes excited by the Fluid Resonance
- 2015
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 32:11, s. 115201-
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Tidskriftsartikel (refereegranskat)abstract
- We apply the Reductive perturbation method to the simple electrostatic ITG mode in an advanced fluid description. The fluid resonance turns out to play a dominant role for the excitation of zonal flows. This is the mechanism recently found to lead to the L-H transition and to the nonlinear Dimit’s upshift. It is important that we have here taken the nonlinear temperature dynamics from the Reynolds stress as the convected diamagnetic flow. This has turned out to be the most relevant effect as found in transport siumulations of the L-H transition, internal transport barriers and Dimits shift. This is the first time that an analytical method is applied to a system which numerically has been found to give the right experimental dynamics.
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