Modern Physics Letters B

Experimental studies of the transitions from a primary quantum Hall (QH) liquid at filling factor ν=1/k (with k an odd integer) to the insulator have indicated a "quantized Hall insulator" (QHI) behavior: while the longitudinal resistivity diverges with decreasing temperature and current bias, the Hall resistivity remains quantized at the value kh/e². We review the experimental results and the theoretical studies addressing this phenomenon. In particular, we discuss a theoretical approach which employs a model of the insulator as a random network of weakly coupled puddles of QH liquid at fixed ν. This model is proved to exhibit a robust quantization of the Hall resistivity, provided the electron transport on the network is incoherent. Subsequent theoretical studies have focused on the controversy whether the assumption of incoherence is necessary. The emergent conclusion is that in the quantum coherent transport regime, quantum interference destroys the QHI as a consequence of localization. Once the localization length becomes much shorter than the dephasing length, the Hall resistivity diverges. We conclude by mentioning some recent experimental observations and open questions.

The near-field distribution of surface plasmon polariton (SPP) on metallic photonic crystal slabs has been studied. Preliminary numerical simulations indicate that the interference of SPP on the exit side of metallic photonic crystal slabs can redistribute the illumination light into nano-scale spatial distribution, which beats the Rayleigh diffraction limit. The electric field distribution of SPP with a resolution of 50 nm was measured by recording the high intensity range into photoresist with a wavelength of 436 nm. Because of the small wavelength of the plasmon wave, a much higher spatial resolution can be obtained, which can provide a new nano-fabrication or nano-storage method by using optical light with a long wavelength.

Three terminators have been tested, square root terminator, quadreture terminator and linear terminator, it was found that the linear terminator is the best, so it was used in calculating local density of states (LDOS) and it's orbital decomposition, alloy average density of states, and energy gap for different anion concentrations for InP lattice matched alloy. The results were compared with our previous calculations of (LDOS), and results from other methods. Energy gap was compared with experimental measurements. A five orbital sp³s* per atom model was used in the tight-binding representation of the Hamiltonian.

The magnetoelectric (ME) effect in a ME composite structure in which a magnetostrictive component is bonded with a piezoelectric component was studied theoretically, based on the hyperbolic nonlinear constitutive relation of magnetostriction and the piezoelectric equations. A quantitative relation was established analytically for the ME effect and the influencing factors, such as the magnetic bias field and the structure dimensions. It was verified that the theoretical model agrees qualitatively with the experimental results published in Ref. 7. It can also be predicted by the model that the ME effect can be improved by optimizing the structure dimensions.

We give a full classification of the possible schemes for obtaining the distribution of multiplets observed in the standard genetic code by symmetry breaking in the context of finite groups, based on an extended notion of partial symmetry breaking that incorporates the intuitive idea of "freezing" first proposed by Francis Crick, which is given a precise mathematical meaning.

A model calculation is given for the energy relaxation of a nonequilibrium distribution of hot electrons prepared in a metallic sample that has been subjected to homogeneous photo-excitation by a femtosecond laser pulse. The model assumes that the photoexcitation creates two interpenetrating electronic subsystems, initially comprising of a dilute energy-wise higher-lying nondegenerate hot electron subsystem, and a relatively dense, lower-lying electron subsystem which is degenerate. The relaxation process is taken to be dominated by the electron–(multi)phonon interaction, resulting in a quasi-continuous electron energy loss to the lattice bath. A novel physical feature of the kinetics considered here is the slowing down of the electron–phonon relaxation in the vicinity of the Fermi energy of the degenerate subsystem, due to the fermionic blocking of the interaction phase space. This leads to a peaking of the calculated hot electron distribution at the Fermi energy. This feature, as well as the entire evolution of the hot electron distribution, may be time-resolved by a pump-probe study. The model is particularly applicable to disordered metallic systems with low electron concentrations and strong electron–phonon coupling, and that are at high temperatures, where the usual two-temperature model^1–3 may not be appropriate.

The effects of annealing temperature on the optical properties of nitrogenated amorphous carbon (a-C:N) films grown on quartz substrates by a novel surface wave microwave plasma chemical vapor deposition (SWMP-CVD) method are reported. The thickness, optical, structural and bonding properties of the as-grown and anneal-treated a-C:N films were measured and compared. The film thickness decreased rapidly with increasing annealing temperature above 350°C. A wide range of optical absorption characteristics is observed, depending on the annealing temperature. The optical band gap of as-grown a-C:N films is approximately 2.8 eV, gradually decreasing to 2.5 eV for the films anneal-treated at 300°C, and beyond that decreasing rapidly down to 0.9 eV at 500°C. The Raman and FTIR spectroscopy measurements have shown that the structural and composition of the films can be tuned by optimizing the annealing temperature. The change of optical, structural and bonding properties of SWMP-CVD-grown a-C:N films with higher annealing temperature was attributed to the fundamental changes in the bonding and band structures of the films.