We introduce a new class of quantum and classical correlation measures by generalizing the reflected entropy to multipartite states. We define the new measures for quantum systems in one spatial dimension. For quantum systems having gravity duals, we show that the holographic duals of these new measures are various types of minimal surfaces consist of different entanglement wedge cross sections. One special generalized reflected entropy is ∆ R , with the holographic dual proportional to the so called multipartite entanglement wedge cross section ∆ W defined before. We then perform a large c computation of ∆ R and find precise agreement with the holographic computation of 2∆ W . This agreement shows another candidate ∆ R as the dual of ∆ W and also supports our holographic conjecture of the new class of generalized reflected entropies.

Ru/BC multilayer mirrors are used for hard X-ray monochromators with moderate spectral resolution and high integral flux. To overcome the problem of large compressive stress inherent in Ru/BC multilayers, a reactive sputtering technique using a mixture working gas of argon and nitrogen with different partial pressures was tested, and the fabricated multilayers had a period of 3 nm. The intrinsic stress was essentially reduced after nitridation and relaxed to zero value at approximately 15% partial pressure of nitrogen in the working gas. Interface roughness was slightly increased which can be caused by the polycrystalline structure inside the nitridated samples. More importantly, the nitridated multilayers showed an enhanced reflectance (67% at 8.04 keV photon energy) as compared with the one fabricated with pure Ar (54%). The structure analysis with transmission electron microscopy and X-ray photoelectron spectroscopy demonstrated that nitrogen incorporated into a multilayer structure was mostly located in the BC layers forming BN compounds, which suppressed the diffusion of boron, stabilized the interfaces and enhanced the reflectance.

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The reflectivity of Al/Zr multilayers is enhanced by the use of a novel structure. The Al layers are divided by insertion of Si layers. In addition, Si barrier layers are inserted at the Al/Zr interfaces (Zr-on-Al and Al-on-Zr). As a result, crystallization of the Al layer is inhibited and that of Zr is enhanced. In grazing incidence x-ray reflectometry, x-ray diffraction, and extreme ultraviolet measurements, the novel multilayers exhibit lower interfacial roughness compared with traditional multilayer structures, and their reflectivity is increased from 48.2% to 50.0% at a 5° angle of incidence. These novel multilayers also have potential applications in other multilayer systems and the semiconductor industry.

Low stress W/Si multilayer mirrors are demanded in the hard X-ray telescopes to achieve the high angular resolution. To reduce the stress of the as-deposited multilayer and maintain a high reflectivity, two groups of low-temperature annealing experiments were performed on the periodic multilayers with a d-spacing of ~3.8 nm. The temperature-dependent experiments show that the 150 °C annealing can slightly increase the reflectivity while the stress reduced only by 24%. Higher temperature annealing induced a larger reduction of the stress and the multilayer reached an almost zero stress state at 250 °C. The stress relaxation was accompanied by a small drop of reflectivity of ≤5% and a period compaction of <0.02 nm. The time-dependent experiments indicate that most of the stress changes occurred within the first 10 minutes while a prolonged annealing is not useful. The X-ray scattering and transmission electron microscopy were further used to study the microstructure changes of the multilayers. It is found that the W/Si multilayer exhibits an amorphous structure before and after annealing, while an enhanced diffusion and intermixing is the main reason for the stress relaxation and structure changes.

The effect of increasing temperature on the structural stability and interactions of two kinds of Al/Zr (Al(1%wtSi)/Zr and Al(Pure)/Zr) multilayer mirrors are investigated. All Al/Zr multilayers annealed from 200^{\circ}C to 500^{\circ}C, were deposited on Si wafers by using direct-current magnetron sputtering technology. A detailed and consistent picture of the thermally induced changes in the microstructure is obtained using an array of complementary measurements including grazing incidence X-ray reflectance, atomic force microscope, X-ray diffraction and high-resolution transmission electron microscopy. The first significant structural changes of two systems are observed at 250^{\circ}C, characterized by asymmetric interlayers appears at interface. At 290^{\circ}C, the interface consisted of amorphous Al-Zr alloy is transformed to amorphous Al-Zr alloy and cubic ZrAl3 in both systems. By 298^{\circ}C of Al(1%wtSi)/Zr and 295^{\circ}C of Al(Pure)/Zr multilayers, the interfacial phases of Al-Zr alloy transform completely into polycrystalline mixtures of hcp-ZrAl2 and cubic-ZrAl3, which smooth the interface boundary and lower the surface roughness in the multilayers. Up to 500^{\circ}C, the multilayer structure still exists in both systems, and the differences between the asymmetric interlayers are much larger in the multilayers. Finally, we discuss the transformation from symmetric to asymmetric in the annealing process for other systems

Reactive sputtering with a mixture of argon and nitrogen (N₂ partial pressure of 4%, 8%, and 15%) as the working gas is used to develop the high reflectance Pd/B₄C multilayers for soft X-ray region application. Compared to the pure Ar fabricated sample, the interface roughness of the nitridated multilayer is slightly increased while the compressive stress is essentially relaxed from -623 MPa (pure Ar) to -85 MPa (15% N₂). A maximum reflectance of 32% is measured at the wavelength of 9.5 nm for the multilayer fabricated with 15% N₂. After storing the multilayers in an air environment for 6-17 months, a distinct aging effect is observed on the nitridated samples. The transmission electron microscopy results indicate that a large part of the top layers of the nitridated samples is deteriorated with severe interdiffusion, essential decrease in d-spacing, and compacted multilayer structure. The deterioration is less pronounced for the multilayers fabricated with a higher ratio of N₂. Energy dispersive X-ray spectroscopy reveals that the concentration of nitrogen and boron in the degraded area is much reduced compared to the intact layers. A primitive model of upward diffusion of nitrogen and boron is proposed to explain the aging effects of the nitridated structure.

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