Huang Xin-Tang

Electronic Structure of Si-C Alloys

We have systematically studied the electronic structure of the ordered Si-C alloys, fourteen models were created according to the different carbon contents. The linear muffin-tin orbitals method was used to calculate their energy band informations. The functional relation of band gap upon carbon contents conflicts with the point of view of Soref [J. Appl. Phys. Lett. 56 (1990) 734], but agrees well with that of Alexanders [Phys. Rev. B 48 (1993) 2207].

Analytical theory of DC SQUID with a resistively shunted inductance driven by thermal noises

An analytical expression for the stationary probability distribution of the DC superconducting quantum interference device (SQUID) with a resistively shunted inductance driven by thermal noise is derived from the two-dimensional Fokker–Planck equation. The effects on the SQUID characteristics subject to a large thermal fluctuation with a noise parameter Γ>0.20 are discussed by taking into account the thermal noise in the accuracy of numerical simulation. This theory is valid for a reduced inductance β≤1. The analytical formulae for the SQUID characteristics, e.g. the circulating current, the average voltage and the voltage modulation, are obtained and discussed. The theory shows that the voltage modulation increases with the shunted inductance more efficiently for a large inductance parameter β and small fluctuation parameter Γ.

Quantum size effect of the magnetism of an electron in a metal layer of the layered compounds M/I/M/I…

The energies and the magnetization of an electron in a piece of metal in the structure of Metal/Insulator/Metal/Insulator… (M/I/M/I…), in a magnetic field, at high temperature, and in range of quantum size thickness of the piece of metal layer have been obtained. The results show that when the thickness of the metal layer becomes smaller, the orbital magnetism of the charged particles which collide with the wall of the metal layer is to vary from diamagnetism to paramagnetism. The smaller the thickness of the metal layer becomes, the more particles will collide with the boundary of the metal layer, and then the paramagnetism becomes stronger. Finally, when the thickness of the metal layer becomes very small (<100 nm), all of the orbital diamagnetism will reverse to paramagnetism, and then the paramagnetization will be almost a maximum constant.

R-W Cosmological Solution for Polytropes

Einstein’s theory of general relativity has given modern physics a consistent and fruitful framwork in which to study cosmology.