In this paper, a two-dimensional square photonic crystal sPCd with superconductor cylinders is proposed to realize tunable negative refraction. Based on the dependence of the superconductors' permittivity on temperatures, photonic band structures thus negative refraction could be tuned by temperatures, whereby the refractive angle could be scanned from positive to negative. The feasibility of the PC operating in infrared and visible regions was discussed. The tunability resulted from the lattice, superconductors, operating frequency, and incident angle may lead the PC to great promise in photoelectronics and superconductor electronic applications.

A two-dimensional square photonic crystal sPCd with magnetically active semiconductor constituents, for example GaAs, is proposed to realize tunable negative refractions. By the Voigt effect, the magnetic-dependent permittivity of the semiconductor, then PC's band structure and equifrequency surface could be tuned by an external magnetic field. Taking a real model into consideration with absorption, the calculation reveals that the refraction could be manipulated from positive to negative, and then to positive by the applied fields. With the tunable negative refraction, tunable superlenses with all angle negative refraction could be established by a relatively small magnetic field s0.262-0.315Td, which might lead to great potential applications in photoelectronic devices.

To realize the hole-mediated ferromagnetism, manganese and nitrogen-codoped ZnO(Zn1-xMnxO:N) films were prepared on sapphire (0001) by reactive radio-frequency (rf) magnetron sputtering from Zn0.97Mn0.03O ceramic targets using N2 gas. X-ray photon spectra reveal that the doped Mn ions are mainly in divalent states and the coexistence of O-Zn and N-Zn bonds in the films. According to the absorption spectra, the band gap of Zn0.97Mn0.03O: N films is about 3.15eV, which is slightly lower than that of ZnO films (3.20eV). Compared with Zn0.97Mn0.03O films, ferromagnetic behavior of Zn0.97Mn0.03O: N films were significantly changed with a coercivity of about 70 Oe, a saturation magnetization of 0.92μB/Mn2) and a remanance over 0.15μB/Mn2) at 300K, while at 10K, they increased to be about 110 Oe, 1.05μB/Mn2) and 0.23μB/Mn2), respectively. However, rapid thermal annealing treatment in pure oxygen results in a significant decrease on the magnetic properties of the films.