The ability to image integrated circuits across different length scales is important for tasks ranging from design validation to failure analysis and quality control. Currently a suite of distinct probes is needed, from optical microscopy for imaging the largest features to electron microscopy for the smallest ones. PSI researchers have now further developed a method pioneered at SLS, ptychographic X-ray laminography, and demonstrate that they can obtain non-destructive 3D views of an entire chip, and then zoom in on arbitrarily chosen subregions of interest to acquire high-resolution images. As a demonstration, they used the technique to first scan a 300 × 300 μm² area of a 16-nm FinFET integrated circuit in low-resolution mode, to subsequently focus on a section of 40-μm diameter, of which they produced a 3D image with 18.9-nm reconstruction resolution.

Colloidal nanocrystals can be conveniently assembled from solutions into densely packed superlattices with widely tunable electronic and optical properties. Researchers from ETH Zurich have now demonstrated that the highly complex vibrational modes of such superstructures can be systematically engineered as well. At SINQ, they performed inelastic neutron scattering experiments in which they characterised the phonon density of states in various nanocrystal superlattices and established that their phononic structure can be well understood with a spring–mass model. With this knowledge at hand, and given that the properties of the superlattices can be controlled in many ways - for example through the composition, size, shape and surface of the nanocrystals - a versatile platform emerges for creating solids with tailored acoustic properties that cannot be achieved in traditional architectures.

Despite years of intense study, FeSe - the structurally simplest iron-based superconductor - continues to hold mysteries. In particular, it is still debated how magnetic and nematic structural order interact, and how each of them affects superconductivity. Fresh insight comes now from muon spin rotation and relaxation experiments at SμS, combined with magnetization measurements. In a study of FeSe_{1– x}S_x, where S-substitution is used as a structural tuning parameter, a substantially extended magnetic dome was found for x ≈ 0.11 when a hydrostatic pressure above ∼0.6 GPa was applied. The magnetic order competes initially with the microscopically coexisting superconducting phase, leading to a local maximum and minimum in T_c. For increasing sulphur content, the local maximum shifts to lower pressures, and by extrapolation magnetism and superconductivity are predicted to coexist at ambient pressure for x ≥ 0.2.

Organic-inorganic ‘hybrid’ perovskites have gained recent attention as a low-cost alternative to silicon solar cells. However, many properties of these materials remain poorly understood. One puzzle is why energy transport in perovskite cells seems to be much less affected by crystal imperfections than in their silicon counterparts. To investigate this question, an international team measured the ultrafast diffuse X-ray scattering of a hybrid perovskite crystal at the Bernina instrument of SwissFEL. The response to impulsive UV-light excitation reveals the disorder hidden inside the crystal lattice. Changes in the diffuse-scattering intensity after photoexcitation were recorded over a wide range of angles, such that different phonon waves could be discerned - providing valuable insight into how the perovskite crystal lattice might 'protect' charges created by light.
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A new endstation for high-resolution angle-resolved photoemission (ARPES) is now in operation at the Surface/Interface Spectroscopy (SIS) beamline. The station, dubbed ULTRA, is based around a 6-axis manipulator capable of operating at temperatures as low as 4 Kelvin. It also features a ScientaOmicron^TM DA30-L analyzer with deflector-based scanning, which can simplify Fermi surface mapping from especially small samples or domains. The cutting-edge performance is achieved with an eye toward flexibility and simplicity for the user, setting a new standard in ARPES instrumentation for probing the electronic structures of quantum materials.

The SINQ guide upgrade continues according to plan: After the 4.5m guide section closest to the cold source was already successfully installed last spring, the two guides for DMC and CAMEA have now been completed. The FOCUS guide in the bunker is also completed, and all remaining guides are ready for installation. The closing of the neutron bunker is now planned for early March.
The beginning of the operation of SINQ is planned for 18 May 2020, and user operations will commence in June/July 2020, with a first proposal submission deadline on January 31, 2020. These proposals will apply for the beam time period I/20 between June-September 2020. The following instruments will be either fully or partially available during that SINQ cycle: HRPT, ZEBRA, POLDI, NEUTRA, ICON, SANS-I, TASP, EIGER and FOCUS. Further information can be obtained here.

The Swiss Muon Source SμS looks back on a very successful year of user operation in 2019. More than 220 experiments could be performed on the five instruments in operation: GPD, GPS, LEM, HAL-9500 and DOLLY. 156 different users from 23 countries came along, with the largest foreign communities coming from the United Kingdom (10%) and Germany (9%).  
The number of new submitted proposals is more than encouraging: a new record of totally 377 proposals were submitted during the year 2019, 199 of them for the recent submission deadline in December. The proposals are now under evaluation and the users can expect to be informed about the results in late February 2020.  

Muonic atoms as laboratories for fundamental physics provide crucial input to quantum electrodynamics, the weak and the strong interaction. Many studies of muonic atoms have relied on the detection of X-rays from the muonic cascade.
For this year's campaign of the muX experiment, the Miniball high-purity germanium detector array was brought from CERN to PSI; benefitting from this unique opportunity due to the long shutdown at CERN. During the seven weeks of the campaign, four different experiments were conducted: The measurements of the unknown charge radii of the radioactive nuclei ²⁴⁸Cm and ²²⁶Ra using microgram targets, measurements of muon capture rates of elements relevant for neutrinoless double-beta decay, elemental analysis of historical artefacts and the measurement of the elusive single photon 2s-1s transition in muonic zinc.

Copyright © 2019, Paul Scherrer Institut PSI

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Contact: PSI User Office, Phone: +41-56-310-4666, Email: useroffice@psi.ch