Setting up strong Josephson coupling in van der Waals materials in close proximity to superconductors offers several opportunities both to inspect fundamental physics and to develop cryogenic quantum technologies. Here we show evidence of Josephson coupling in a planar few-layer black phosphorus junction. The planar geometry allows us to probe the junction behavior by means of external gates, at different carrier concentrations. Clear signatures of Josephson coupling are demonstrated by measuring supercurrent flow through the junction at milli-Kelvin temperatures. Manifestation of a Fraunhofer pattern with a transverse magnetic field is also reported, confirming the Josephson coupling. These findings represent evidence of proximity Josephson coupling in a planar junction based on a van der Waals material beyond graphene and will expedite further studies, exploiting the peculiar properties of exfoliated black phosphorus thin flakes.

Hydrogen spillover and storage for single-site metal catalysts, including single-atom catalysts (SACs) and single nanocluster catalysts, have been elucidated for various supports but remain poorly understood for inert carbon supports. Here, we use synchrotron radiation-based methods to investigate the role of single-site Ti catalysts on graphene for hydrogen spillover and storage. Our insitu angle-resolved photoemission spectra results demonstrate a bandgap opening and the X-ray absorption spectra reveal the formation of C−H bonds, both indicating the partial graphene hydrogenation. With increasing Ti deposition and H2 exposure, the Ti atoms tend to aggregate to form nanocluster catalysts and yield 13.5% sp 3 -hybridized carbon atoms corresponding to a hydrogen-storage capacity of 1.11 wt% (excluding the weight of the Ti nanoclusters [1]). Our results demonstrate how a simple spillover process at Ti SACs can lead to covalent hydrogen bonding on graphene, thereby providing a strategy for a rational design of carbon-supported single-site catalysts.

The continuous miniaturization and increasing complexity of the materials used in modern technology requires to have access to chemical composition, electronic structure, magnetization, and fluctuations in these properties at sub-micron and nanometer scales. X-ray photoemission electron microscopy (XPEEM) can provide this information. The recent years have seen a strong increase in XPEEM activities worldwide. This paper reviews the present situation and future developments of XPEEM in combination with synchrotron radiation. In particular, the role of energy filtering, aberration correction, and temporal resolution is discussed. 1．IntroductionX-ray photoelectron spectroscopy (XPS) and the related technique , X-ray absorption spectroscopy (XAS), are powerful tools for the analysis of surfaces, as widely discussed in this issue. In a traditional experimental setup, the spectroscopic signal is obtained from a spot of some 100 µm to millimeters in diameter, and therefore averages over this area. On the other hand, the progress in modern nanotechnology has fueled an evergrowing demand to perform XPS and XAS from areas as small as the smallest building blocks of those nanostructures . This has triggered the development of special instruments which combine spectroscopy and microscopy and allow to perform XPS and XAS with the highest possible lateral resolution of less than 100 nm. 1)More than 10 years ago, two basic, complemetary design principles have been identified to achieve this goal:2) the scanning and the direct imaging type instruments. In the scanning type instruments the photon beam is demagnified, i.e. the X-rays are focused by an optical system (like a Fresnel zone plate or a Schwarzschild objective) on a small spot on the sample. The photoelectrons excited from this area are then collected by a detector. The lateral resolution of the instrument is given by the size of the illuminated area. A surface map can be obtained by scanning the sample relative to the beam. More details of this kind of instruments can be found in the article of T. Munakata in this issue.

Hybrid superconductor/semiconductor devices constitute a powerful platform to investigate the emergence of new topological state of matter. Among all possible semiconductor materials, InAs represents a promising choice, owing to its high quality, large g-factor and spin-orbit component. Here, we report on InAs-based devices both in one-dimensional and two-dimensional configurations. In the former, low-temperature measurements on a suspended nanowire are presented, inspecting the intrinsic spin-orbit contribution of the system. In the latter, Josephson Junctions between two Nb contacts comprising an InAs quantum well are investigated. Supercurrent flow is reported, with Nb critical temperature up to T c ∼ 8 K. Multiple Andreev reflection signals are observed in the dissipative regime. In both systems, we show that the presence of external gates represents a useful knob, allowing for wide tunability and control of device properties, such as spin-orbit coherence length or supercurrent amplitude.Among all semiconductor materials, InAs plays a prominent role due to its low effective mass, strong spinorbit coupling, and high Landé g-factor. 16-21 Moreover, hybrid superconductor/semiconductor devices require high quality contacts with low normal/superconductor (N/S) interface resistance, to guarantee a robust proximity effect, and eventually large electron mean free path (MFP). 20,22 It has been shown that InAs represents the ideal choice for building hybrid devices, owing to the lack of a Schottky barrier at the interface with the metal, combined with the small effective mass and large spin-orbit coupling of this semiconductor. 16-21 Epitaxial Al/InAs heterostructures were realized that show an exceptionally transparent superconductor-semiconductor

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