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A magneto-optic spatial light modulator driven by an electric field is fabricated by using the electrostrictive effect of [Pb(Zr[SUB0.52]Ti[SUB0.48])O[SUB3]] (PZT) thin film. As the stress field induced by the PZT thin film reduces the anisotropy energy of the structured garnet film, we find that the pixels can be easily switched in accordance with or without the small external bias field. When peak-to-peak 8 V at the X and Y conductors is applied with the external bias field of 40 Oe at the fabricated device, the selected pixel is switched independently. [ABSTRACT FROM AUTHOR]

Nonlinear-optical manifestations of the Borrmann effect that are consequences of the spectral dependence of the spatial distributions of the electromagnetic field in a structure are observed in one-dimensional photonic crystals. The spectrum of the light self-focusing effect corresponding to the propagation-matrix calculations has been measured near the edge of the photonic gap. [ABSTRACT FROM AUTHOR]

Current transport properties in Y1Ba2Cu3O7δ (YBCO) coated conductors obtained by pulsed laser deposition process on a CeO2 capped Gd2Zr2O7-IBAD template have been studied by spatially resolved measurements. We utilized low temperature scanning laser microscopy along with laser induced Seebeck effect imaging and scanning SQUID microscopy that allow us to visualize 1) distributed flux flow dissipation, 2) current blocking obstacles and 3) local current flow, respectively. Combination of those measurements leads deep insights into current limiting mechanism in the coated conductor. Our results show that non-uniform current flow due to spatially distributed obstacles is responsible for the dissipation, whereas grain connectivity in each YBCO grains is not the limiting factor. Typical period of those obstacles is several tens μm to hundreds μm. Detailed correlation between local current flow and dissipation has been observed. Present methods have great potential as tools for basic understanding of current limiting mechanisms in the coated conductors. [ABSTRACT FROM AUTHOR]

Current transport properties in 200 A-200 m-class IBAD-YBCO coated conductor (CC) have been investigated over a wide range of temperature and magnetic flux density up to 26 T. YBCO CC fabricated by reel-to-reel pulsed laser deposition equipment with a multi-plume and multi-turn deposition system showed high critical current of 245 A in length of 212.6 m. Critical current density, Jc, in 5 T parallel to c-axis at 65 K and 4.2 K were 0.44 MA/cm2 and 5.5 MA/cm2, respectively. Moreover, even in very high magnetic flux density, the superior Jc property remains at lower temperature, e.g. Jc at 4.2 K in 26 T was 2 MA/cm2. We also showed analytical expressions of electric field vs. current density (E–J) characteristics based on a framework of percolation model and scaling law of the flux pinning properties. Using the expressions, E–J characteristics and Jc value at any conditions of temperature and magnetic flux density can be predicted quantitatively. [ABSTRACT FROM AUTHOR]

The author’s recent studies on the critical current properties in Bi-2223 multifilamentary tapes as well as YBCO coated IBAD tapes have been reviewed. Extended electric field vs. current density (E–J) characteristics were studied over wide range of temperature, T, magnetic field, B, and angle, θ. Based on the analysis of statistic Jc distribution and scaling, we derived an analytical expression for J as a function of E, T, B, and θ. This method allows us to describe and extrapolate the nonlinear E–J characteristics even in extremely low E region and/or high B region based on rather simple measurements. [Copyright &y& Elsevier]

Quantum wells with graded barriers are demonstrated as a means to control both the transition energy and electron-hole wave function overlap for quantum wells with an intrinsic internal electric field. In the case of c-axis grown ZnO/ZnMgO quantum wells, the graded barriers are produced by stepping the magnesium composition during the growth process. Four quantum wells with different structures are examined, where each well has similar transition energy, yet a wide range of wave function overlaps are observed. Photoluminescence and time resolved photoluminescence show good agreement with calculations. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated critical current property in YBa2Cu3O7− δ (YBCO) coated conductor fabricated by improved metal organic deposition using trifluoroacetates (TFA–MOD) process optimizing conditions such as solution compositions. The electric field vs. current density (E–J) characteristic measurement was carried out at wide range of temperature, T, and magnetic field, B. Critical current density, J c, reached 3.8×1010 A/m2 at 77K in self-field for 1.2μm thick YBCO layer. In-field J c is also improved by this new process. From the analysis of E–J characteristics, we have found out that the shape of statistical distribution of J c in the new process becomes sharper than that of the previous one. These results indicate that the uniformity of YBCO layer is improved by the new process. Furthermore, analytical expression of E–J characteristics, which is based on a percolation model and a scaling law of the pinning force density, shows good agreement with the experimental results. This allows us to predict the critical current property at arbitrary conditions of T and B even if we couldnot have measured data. For example, it is predicted that J c could be about 1×1010 A/m2 at 4.2K and 30T parallel to the c-axis. [Copyright &y& Elsevier]

Abstract: We have investigated electric field criterion of in-plane critical current density in a coated conductor characterized by scanning Hall-probe microscopy (SHPM). From remanent field distribution and its relaxation measurements, we could obtain critical current distribution and induced electric field simultaneously by considering the Biot-Savart law and the Faraday’s law, respectively. These results lead us to evaluate a distribution of local critical current density and the corresponding criterion of electric field. As a result, it was found that the electric field criterion for the SHPM analysis was several orders lower than that used in the conventional 4-probe resistive method. However, the data point obtained by the SHPM shows good agreement with E–J curve analytically extended from the measurements by the 4-probe method. This means that we could characterize in-plane distribution of critical current density in a coated conductor at an electric field criterion quantitatively by this method in a nondestructive manner. These findings will be very important information since the uniformity of local critical current density in a coated conductor at extremely low electric fields is a key issue (1) especially for DC applications, (2) for quality control of coated conductors, and (3) for the standardization of the characterization of critical current among different methods. [Copyright &y& Elsevier]

The E–J characteristics were measured for a YBCO coated-conductor by using AC inductive method of third-harmonic voltage. The results are compared with the measurements obtained by the four probe method and DC relaxation method of magnetization. The results by three kinds of measurements meet approximately on a single curve and E–J curve in a wide range of electric field is obtained. Hence, the third-harmonic voltage method is useful for a continuous measurement of Jc property of long coated tape. The obtained E–J characteristics are argued. [Copyright &y& Elsevier]

The E–J characteristics were measured for a YBCO-coated conductor by using the four probe method and the relaxation method of DC magnetization. The result on the latter measurement at extremely low electric fields was theoretically analyzed based on the flux creep-flow model. From the result on n-value the flux lines in YBCO are considered to be in the glass state even at high fields. The apparent pinning potential U0* estimated from the relaxation of DC magnetization is much larger than that of Bi-2223. The present theoretical analysis clarifies a much stronger flux pinning and a higher dimensionality of YBCO in comparison with Bi-2223. [Copyright &y& Elsevier]

The field distribution of a light wave near a magnetic defect in a one-dimensional photonic crystal is analyzed. It is shown that, by properly varying the magnetic defect thickness or the parameters of the photonic crystal surrounding the defect, one can create a situation where the electric field of a light wave will be localized predominantly inside the magnetic layer or, conversely, in the immediate vicinity of the layer surface. This opens up possibilities for optimizing the Q factor of a magnetic microcavity in the presence of dissipation in the magnetic layer and, hence, for enhancing the linear and nonlinear magneto-optical effects. The possibility of separating the contributions from the surface and volume of the magnetic material to the nonlinear magnetooptical properties by properly varying the field distribution over the defect thickness is discussed. [ABSTRACT FROM AUTHOR]