Numerical study of negative index material with low loss and polarization-independence in mid-infrared spectrum

We engineer numerically a negative index material （NIM） based on a square ring pairs （SRP） array and a thin wire net pairs （WNP）. This metamaterial exhibits polarization-independence and low loss that is characterized by a figure of merit （FOM） up to 8.2 in mid-infrared spectrum.     

Study of Phase Transition Properties in Epitaxial Ferroelectric Film

Based on the transverse Ising model and using decoupling approximation to the Fermi-type Green＇s function, we study the phase transition properties of the epitaxial ferroeleetric film with one substrate. A general recursive equation of the ferroelectric thin film with two n-layer materials is obtained, which enables us to study the phase transition properties for any number layers for epitaxial ferroelectric thin film. With the help of this equation, we analyze the effect of the exchange interaction and the transverse field in the phase diagram, the influence to the polarizations and Curie temperature numerically. The results show that epitaxial ferroelectric film are able to induce a strong increase or decrease of Curie temperature to different exchange interactions and transverse fields within the epitaxial film layers. The theoretical results are in reasonable accordance with experimental data of different ferroelectric thin film.