Recent Advances in Condensed Matter Physics

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Authors: Ping Zhu
Abstract: A new model of the projectile motion for the resistance being proportional to the square of velocity components is investigated. In the course of the projectile motion, the direction of the resistance and the direction of the velocity are not entirely the opposite and on a straight line, in which the deviation angle exists. The size and the interrelation of velocity components determinate the size of the deviation angle, where deviation angles of some points take zeroes and another points take maximum values. The article makes deeply analysis for the new projectile model of velocity components, and gives interesting results.
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Authors: Xian Bin Zhang, Wen Jie Wu, Ning Kang Deng, Xu Yan Wei, Guan Qi Wang
Abstract: The electronic structure and optical properties of GaP were calculated using generalized gradients in density functional theory. The Bonn effective charge, optical frequency dielectric constant and the LO-TO splitting value were calculated by density functional theory perturbation method.
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Authors: Zhen Gang Guo, Hong Mei Qiu
Abstract: The structure, martensitic transition and magnetic properties of Ni44Co6Mn40CuxSn10-x quinary alloy are investigated systematically. The substitution of Cu for Sn is found to reduce the symmetry of crystal structure, showing an evolution from cubic to tetragonal phase at room temperature. Two magnetic transitions were observed in the alloys, martensitic transition and Curie transition. The critical temperatures of martensitic transformation are found to increase nearly linearly with increasing valence electron concentration caused by Cu substitution for Sn, while Curie temperature of the austenitic phase decreases with the increasing Cu content in the alloys. The Ni44Co6Mn40CuxSn10-x alloys have a large magnetic entropy change across the martensitic transition, reaching 26.8 Jkg-1K-1 under a field change of 3T, because of the strong coupling between structure and magnetism, which shows a great applicable prosperity in magnetic refrigeration technology.
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Authors: Lei Liu, Yan Ju Ji, Yi Fan Liu
Abstract: The effect of strain on the band structure of the GeH monolayer has been investigated by first-principles calculations based on density functional theory. The results show that the change of the band gap under the zigzag strain, the armchair strain and the biaxial strain is nonlinear. The effect of the biaxial strain on the band gap is the most obvious. In addition, the changes of energy under the three kinds of strain are asymmetric and the biaxial strain make the energy change the most. This work has significant implication of strain to tune optical catalytic properties of GeH monolayer.
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Authors: Yu Lan, Lü Lin Kuang
Abstract: Within the kinetic energy driven superconducting mechanism, we have studied the temperature dependence of commensurate magnetic resonance in cuprate superconductors. It is shown that the commensurate magnetic resonance peak at the antiferromagnetic wave vector point persists in the superconducting state until the temperature rises to the superconducting transition temperature $T_{\rm c}$. The intensity of the resonance peak decreases with increasing temperature which is just like the temperature dependence of the superconducting gap parameter. Our results are in qualitative agreement with the inelastic neutron scattering experimental data and reflect that the commensurate magnetic resonance is closely related to the creation of the charge carrier pairs and thus the superconducting mechanism of cuprate superconductors.
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Authors: Huan You Wang, Qiao Lai Tan, Gui Jin
Abstract: InGaN/GaN multiquantum well (MQW) structures have been grown on cone-shaped patterned sapphire substrates (CPSS) by metalorganic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) results, we found that most of the threading dislocations (TDs) in the trench region of the CPSS were bent by lateral growth mode. Also the staircase-like TDs were observed near the slant region of the cone pattern, they converged at the slope of the cone patterned region by staircase-upward propagation, which seems to effectively prevent TDs from vertical propagation in the trench region. The associated dislocation runs up into the overgrown GaN layer and MQW, and some (a+c) dislocations were shown to decompose inside the multi-quantum well, giving rise to a misfit segment in the c-plane and a V-shape defect. From cross-sectional TEM, we found that all V defects are not always connected with TDs at their bottom, some V defects are generated from the stacking mismatch boundaries induced by stacking faults which are formed within the MQW due to the strain relaxation.
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Authors: Ahmad Ainurofiq, Rachmat Mauludin, Diky Mudhakir, Arif Budi Setianto, Sundani Nurono Soewandhi
Abstract: This work studied the effect of compression force on the desloratadine (DES) and its multi-component crystal (MCC) formulation and focused on the molecular crystal behavior of DES and MCC after compression. Crystallinity behavior of drugs in a mechanical process is to be interesting manner. In this research, DES and MCC were compressed using hydraulic presser equipped with 13 mm flat-face punch under different compression pressures in a range of 25 – 350 MPa. The solid state of DES and its MCC was evaluated using powder X-ray diffraction (XRD) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Single XRD was carried out to confirm the molecular structure of crystal lattice. Powder XRD diffractogram under different compression forces was compared to the crystallinity degree, crystallite size and peak broadening. Those parameters were processed using Origin software. Crystallinity degree was calculated using Ruland’s methods, meanwhile, the crystallinity size was calculated using Scherrer’s equation after corrected to the broadening (full width at half maximum; FWHM) and diffraction baseline. As increasing the compression force, degree and size of crystallinity and FWHM were altered. In addition, the degree of crystallinity and crystallite size of DES and MCC decreased, while the FWHM increased. Furthermore, alteration of PXRD in DES was higher than that of MCC which had no alteration as increase as the compression force. FTIR result showed that neither DES nor MCC had no significant alteration after compression. However, the tabletability of MCC was better than DES owing to the potential slip plane of MCC.
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Authors: Shao Bo Chen, Kai Li Yao, Ping Huang, Ze Lan Jiang, Shi Lian Lv, Zheng Song Luo
Abstract: According to first-principle based on the density functional theory, the magnetic and optical properties of single layer CrSi2 are calculated and analyzed by plane wave pseudo potential method. The band structure, density of state, optical absorption spectra, reflectivity and energy loss function of single layer CrSi2 are obtained. The results show that single layer CrSi2 has the properties of metal and magnetism. The calculations of optical properties of single layer CrSi2 material deduce that it can absorb photons which belong to visible to ultraviolet region, even in far-infrared and far-ultraviolet regions. Single layer CrSi2 has a good optical permeability to photon (with energy from 13 to 40eV), which shows that single layer CrSi2 is suitable for optoelectronic devices, especially in infrared and vacuum ultraviolet detection applications.
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Authors: Sen Wang, Huan Qing Cui, Ying Yang, Li Cai
Abstract: We propose an input interface circuit that can provide input signals for the emerging all spin logic (ASL) devices. It consists of metal wires that are used for the transmission of electrical signals and magnetic tunnel junction that are used to transform electrical signals into input signals of ASL devices. The operation of input interface is validated by using a coupled spin-transport/magneto-dynamics model. A salient advantage of the proposed input interface is its ability to shorten the length of spin channel for spin transmission and avoid the complex fan-out structure when multiple identical input signals are needed. This input interface is especially useful for the design of large scale ASL circuits, in which many identical units are needed.
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