Broadband GHz frequency characterizations of Permalloy nanorods’ array

The radio frequency characteristics of Permalloy nanorods’ array have been examined by coplanar waveguide (CPW) cell. The Permalloy nanorods’ array was grown in anodic aluminum oxide porous templates with a diameter of 20 nm. As the Permalloy nanorods’ array was placed on CPW, the characteristic impedances of the CPW were changed from 50 to at 1 GHz. The magnitude of inductance was decreased from 3 GHz and the capacitance was increased up to twice in comparison with that of CPW. The signal attenuations were abruptly increased over 1 GHz. The propagation wavelengths due to the insertion of Permalloy nanorods’ array were decreased about 30% at 1 GHz in comparison with that of CPW without magnetic materials.     

Role of annealing environment and partial pressure on structure and optical performance of TiO2 thin films fabricated by rf sputter method

Influences of the different annealing ambient (in air, 1 bar, 2 bar, 3 bar and 4 bar oxygen partial pressure) on the titanium dioxide (TiO₂) thin films deposited on soda lime glass by standard radio frequency (rf) magnetron reactive sputtering method at 100 watt were investigated by means of X–ray diffractometer (XRD), ultra violet spectrometer (UV–vis), and Scanning Electron Microscopy (SEM). It was found that either optical properties or energy band gaps of the films enhanced with increase in the oxygen partial pressure up to 3 bar. The energy band gaps of the films (except for the film annealed in 4 bar oxygen partial pressure) became larger than the film annealed in atmospheric pressure. The best transmission was observed for the thin film annealed in 3 bar oxygen partial pressure. Moreover, not only was grain–like structure found to be more dominant than dot–like structure but also growth of anatase phase was observed instead of that of the rutile phase with increasing oxygen partial pressure up to 3 bar. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

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利用分子动力学方法模拟了碳原子与碳氢薄膜的作用过程。探讨了不同入射能量对碳原子与碳氢薄膜相互作用的影响。模拟结果表明碳原子与碳氢薄膜作用会在表面形成碳薄膜。随着入射能量的增加,碳薄膜厚度变薄。在碳薄膜中碳原子的成键形式主要为Csp2-Csp2和Csp2-Csp3,随入射能量的增加,碳原子键价结合形式从Csp2-Csp2向Csp2-Csp3转化。     

Direct and inverse measurement of thin films magnetostriction

Two techniques of measurements of thin film magnetostriction are compared: direct, when changes of the substrate curvature caused by the film magnetization are controlled, and inverse (“indirect”), when the modification of the magnetic anisotropy induced by the substrate deformation (usually bending) is measured. We demonstrate how both the elastic strength of the substrate and the effective magneto-mechanical coupling between the substrate deformation and magnetic anisotropy of the film depend on different conditions of bending. Equations to be used for magnetostriction value determination in typical cases are given and critical parameters for the corresponding approximations are identified.     

Monte Carlo study of the triangular XY vector Blume-Emery-Griffiths model

The vectorial generalization of the Blume-Emery-Griffiths model, proposed by Berker and Nelson to describe the behavior of films of ³He-⁴He mixtures, is studied by Monte Carlo simulations on the triangular lattice. The temperature versus chemical potential plane phase diagram, for a biquadratic coupling constant equal to the bilinear coupling constant, presents a Berezinzkii-Kosterlitz-Thouless transition line that ends in a first-order transition line at a critical end point. This first-order transition line, on the other hand, terminates at a single critical point. No tricritical point has been detected. The critical exponent η as a function of temperature is independent of the chemical potential.