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A simple tight-binding approach to topological superconductivity in monolayer MoS2

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Chinese Physics B 2020年第2期29卷 425-431页

作者： h.simchi Department of Physics Iran University of Science and TechnologyNarmakTehran 16844Iran Iran Semicondutor Technology Center Tehran 19575-199Iran

Monolayer molybdenum disulfide(MoS2)has a honeycomb crystal ***,with considering the triangular sublattice of molybdenum atoms,a simple tight-binding hamiltonian is introduced(derived)for studying the phase transition and topological superconductivity in MoS2 under uniaxial *** is shown that spin-singlet p+ip wave phase is a topological superconducting phase with nonzero Chern *** the chemical potential is greater(smaller)than the spin-orbit coupling(SOC)strength,the Chern number is equal to four(two)and otherwise it is equal to ***,the results show that,if the superconductivity energy gap is smaller than the SOC strength and the chemical potential is greater than the SOC strength,the zero energy Majorana states ***,we show that the topological superconducting phase is preserved under uniaxial strain.

关键词： MoS2 topological superconductivity Chern number band inversion

The Magnetic Field Effects on Radially Symmetric Core-Shell-Shell Structure

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Optics and Photonics Journal 2011年第1期1卷 5-10页

作者： hamidreza simchi Mahdi Smaeilzadeh Mehdi h. Saani Semiconductor Component Industry Iran University of Science and Technology University

In this paper, we modeled a core/shell/shell structure with cylindrical Schrodinger-Poisson coupled equation when a magnetic field is (and is not) applied along its axis. We showed the electron density is peaked near the outer surface of the channel when the magnetic field is applied. Therefore one may make a nano-device which its electrons move only on its outer surface. Also we applied a gate voltage to the device and showed a higher threshold voltage (to turn on the device) is necessary when a magnetic field is applied. This is because of the increase in the lowest energy level similar to the size quantization. i.e a device with longer channel looks like a device with shorter channel if it is placed in a magnetic field parallel to its axis.

关键词： Naowire Core-Shell-Shell Structure Self-Consistent Calculation Quantum Capacitance

Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid

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Transactions of Nonferrous Metals Society of China 2022年第7期32卷 2216-2228页

作者： Zanko ROUEIN hassan JAFARI Fatemehsadat PIShBIN Rahim MOhAMMADI Abdolreza simchi Department of Materials Engineering Faculty of Materials Engineering and Interdisciplinary SciencesShahid Rajaee Teacher Training University16785-136TehranIran School of Metallurgy and Materials Engineering College of EngineeringUniversity of Tehran11155-4563TehranIran Department of Materials Science and Engineering Sharif University of Technology11365-11155TehranIran Institute for Nanoscience and Nanotechnology Sharif University of TechnologyAzadi Avenue11365-8639TehranIran

The biodegradation behavior of Mg,coated by polymethyl methacrylate as well as polymethyl methacrylate(PMMA)−bioactive glass(BG)composite was *** deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical *** deposited coatings were characterized using SEM,EDS,FTIR,and water contact angle *** behavior study of the coated Mg was performed using linear polarization,impedance spectroscopy,and immersion tests in simulated body *** compact and homogeneous composite coating was developed as evidenced by electron microscopy *** water contact angle measurement showed a 44°increase in the contact angle of the composite coated Mg compared to the uncoated *** composite coating was covered by a bone-like hydroxyapatite layer after 336 h,indicating that the coating has an excellent in vitro *** electrochemical testing results confirmed a significant reduction,96.9%,in the biodegradation rate of Mg coated with the composite prepared from 45 g/L PMMA+3.5 g/L 45S5 GB suspension compared to that of the uncoated ***,the composite coated Mg can be proposed as a promising material for biodegradable implant application.

关键词： magnesium alloy polymethyl methacrylate bioactive glass composite coating electrophoretic deposition biodegradation

Microstructural evolution of Al-20Si-5Fe alloy during rapid solidification and hot consolidation

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Rare Metals 2009年第6期28卷 639-645页

作者： M.Rajabi M.Vahidi A.simchi P.Davami Department of Materials Science and Engineering Sharif University of Technology Institute for Nanoscience and Nanotechnology (INST) Sharif University of Technology

Al-20Si-5Fe melt was rapidly solidified into particles and ribbons and then consolidated to near full density by hot pressing at 400℃/250 MPa/1 h. According to the eutectic-growth and dendritic-growth velocity models, the solidification front velocity and the amount of undercooling were estimated for the particles with different sizes. Values of 0.43-1.2 cm/s and 15-28 K were obtained. The secondary dendrite arm spacing revealed a cooling rate of 6 × 10^5 K/s for the particles with an average size of 20 μm. Solidification models for the ribbons yielded a cooling rate of 5 × 10^7 K/s. As a result of the higher cooling rate, the melt-spun ribbons exhibited considerable microstructural refinement and modification. The size of the primary silicon decreased from approximately 1μm to 30 nm while the formation of iron-containing intermetallic compounds was suppressed. Supersaturation of the aluminum matrix in an amount of-7 at.% Si was noticed from the XRD patterns During the hot consolidation process, coarsening of the primary silicon particles and precipitation of β-Al5FeSi phase were observed. Evaluation of the compressive strength and hardness of the alloy indicated an improvement in mechanical properties due to the microstructural modification.

关键词： Al-Si-Fe alloy rapid solidification cooling rate microstructure mechanical properties