Lamellar Multilayer Gratings (LMG) offer improved resolution for soft-x-ray (SXR) monochromatization, while maintaining a high reflection efficiency in comparison to conventional multilayer mirrors (MM). We previously used a Coupled-Waves Approach (CWA) to calculate SXR diffraction by LMGs and identified a single-order regime in which the incident wave only excites a single diffraction order. We showed that in this regime the angular width of the zerothorder diffraction peak simply scales linearly with Γ (lamel-to-period ratio) without loss of peak reflectivity. However, the number of bi-layers must then be increased by a factor of 1/Γ. Optimal LMG resolution and reflectivity is obtained in this single-order regime, requiring grating periods of only a few hundred nm, lamel widths < 100nm and lamel heights > 1μm [1]. For the fabrication of LMGs with these dimensions, we use a novel process based on UV-NanoImprint Lithography (UV-NIL) and Bosch-type Deep Reactive Ion Etching (DRIE). Successful fabrication of LMGs with periods down to 200nm, line widths of 60nm and multilayer stack heights of 1μm is demonstrated. SXR reflectivity measurements were performed on these LMGs at the PTB beamline at the BESSYII synchrotron facility. The measurements demonstrate an improvement in resolution by a factor 3,5 compared to conventional MMs. Further analysis of the SXR reflectivity measurements is currently being performed.

Integrated dc SQUID magnetometer with a high slew rate Rev. Sci. Instrum. 55, 952 (1984);

Double relaxation oscillation superconducting quantum interference devices (DROSs) with a gradiometric signal SQUID and either a reference SQUID or a reference junction will be presented in this article. The devices are user friendly, particularly those with a reference junction. Because of the large flux-to-voltage transfer of ∂V/∂Φ=0.7–1 mV/Φ0, the devices can be operated in a flux locked loop based on direct voltage readout without loss of sensitivity. The typical white flux noise of the DROSs amounts to √SΦ=5–6μΦ0/√Hz, which corresponds to an energy resolution ε=SΦ/2Lsq≃200 h. Coupled to an external planar first-order gradiometer, a white magnetic field sensitivity of √SB&lt;2 fT/√Hz was measured inside a magnetically shielded room.

YBa2Cu3O7, based monolithic flux transformer-coupled high-T, dc SQUID magnetometers operating up to 73 K have been realized. The devices are characterized by high values of the modulation voltage, up to 32 pV at 40 K. A minimal white noise level of 0.10 pT/dHz was obtained above 200 Hz, and 0.64 pT/dHz at 1 Hz and 55 K. The temperature dependence of the modulation voltage, the effective sensing area and the field sensitivity are discussed. Model-calculations have been performed to investigate high frequency resonances in the washer-input coil structure. Methods for damping are considered.

Low-temperature scanning laser microscopy has been used to investigate the spatial variation of the critical temperature Tc and critical current Ic in thin-film high-To multilayer structures that include dielectric layers. The method is described and measurements are presented on an YBa2Cu307_x-based multiturn coil with SrTiO3 insulating layer. We found that the critical temperature Tc of the YBa2Cu307_x tOp layer, from which the return strip of the coil is formed, is higher than that of the YBa2Cu307_x base layer. The critical current of the coil is limited by the quality of the YBa2Cu3OT_x base layer and not by the edges of the crossovers. 0921-4534/94/$07.00