Modern Physics Letters B

The detonation of carbon- or nitrogen-containing explosives not only produces powerful shock waves but also provides elemental building blocks and a unique high-pressure and high-temperature physical environment for the construction of various nanostructures. This review highlights the situation and key progresses in the detonation approach towards diamond nanoparticles, graphitic carbon nanotubes, fullerene molecules, and gallium nitride nanocrystals. Further extension of the peaceful-use detonation applications and rational reactor design are also proposed.

The bilayer effects of CuO₂ planes in high-T_c superconductors are investigated. The interaction between a CuO₂ bilayer is found to induce a subgap far below the superconducting transition temperature T_c. It is also shown that zero-bias-conductance-peaks (ZBCP) above T_c are due to a Kondo-type effect as for low-T_c superconductors, but ZBCP far below T_c originating from this bilayer effects are different from traditional explanations.

In this article, we perform a self-consistent calculation for the self-energy, based on the pairing mechanism for the two-dimensional phenomenological model below half filling. The non-Fermi versus Fermi liquid behavior is analyzed and the self-energies are compared. We also investigate the doping dependence of the pseudogap in the underdoped regime of the phase diagram of cuprates superconductors. Comparing the obtained results with experimental data, it is found that Δ_pg scales with characteristic temperature T*.

Current perpendicular-to-plane (CPP) magnetoresistance (MR) of La_0.7Ca_0.3MnO₃/LaNiO₃ superlattices sandwiched between two YBa₂Cu₃O₇ thin film electrodes is reported. The CPP-MR in the temperature window of 20 K to 80 K is larger by a factor of 7~15 compared to current-in-plane (CIP) MR. Both CPP and CIP-magnetoresistance decrease with temperature below ~ 20 K. The MR at T<40 K is also strongly hysteretic and does not saturate even at 4 Tesla. Measurements of saturation moment and modeling of the perpendicular-to-plane resistance suggest disorder at the ferromagnetic non-magnetic layer interfaces which dominate the MR. The relative orientation of magnetization in the ferromagnetic layers seems to play only a subservient role in the creation of magnetoresistance.

The surface structure of Ag/W(100) has been studied using LEED and Low Energy Ion Scattering Spectroscopy (ISS). We find that Ag coverages are saturated at 0.5 ML after annealing at 800°C regardless of the initial coverages between 0.7~1.0 ML. We observe a c(2×2) image after annealing the Ag/W(100) sample at 800°C. Using the ISS technique the adsorption site of Ag on the c(2×2) surface is found to be the center of the nearest two atoms on the W(100) surface. The height of the Ag adsorption layer is 1.58 Å above the W(100) surface.

A suitable heating condition designed for a particular type of ruby is used to enhance the quality to increase its value. Heating Vietnamese rubies in an oxygen atmosphere may improve color and clarity, and thus increase their prices. The color of rubies is due to the presence of trace amounts of Cr³⁺. Fe³⁺ yields a pale yellow color and the charge transfer mechanism between Fe²⁺ and Ti⁴⁺ gives ruby an undesirable bluish color. Reducing this mechanism is possible by heating the ruby in oxygen so that most of the Fe²⁺ is converted into Fe³⁺ ions and thus they appear a more intense red. By using XRD we found that the c/a ratio of the hexagonal structure was smallest after heat treatment at 1300°C. The number of Fe²⁺ ions converted to Fe³⁺ was detected by an electron spin resonance spectrometer and found to increase with temperature. The ruby appeared a most intense red after heating at 1500°C for 12 hours. The color change is due to both the decrease in c/a ratio and the increase in the number of Fe³⁺ ions. ESR experiments on ruby crystals by rotation about their c-axis show that Fe³⁺ ions are a little off axis before heat treatment. After heat treatment at 1300°C they move to new asymmetric equilibrium positions towards larger O^2- triangles. It is not clear, however, if this Fe³⁺ movement is related to the change in color. The asymmetry may arise due to some O^2- vacancies.

In this paper, we calculate the entanglement-assisted classical information capacity of the amplitude damping channel and compare it with the particular mutual information which is considered as the entanglement-assisted classical information capacity of this channel in Ref. 6. It is shown that the difference between them is very small. In addition, we point out that using partial symmetry and concavity of mutual information derived from the dense coding scheme, one can simplify the calculation of entanglement-assisted classical information capacities for non-unitary-covariant quantum noisy channels.