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Soft X-ray experiments at synchrotron light sources are essential for a wide range of research fields. However, commercially available detectors for this energy range often cannot deliver the necessary combination of quantum efficiency, signal-to-noise ratio, dynamic range, speed, and radiation hardness within a single system. While hybrid detectors have addressed these challenges effectively in the hard X-ray regime, specifically with single photon counting pixel detectors extensively used in high-performance synchrotron applications, similar solutions are desired for energies below 2 keV. In this work, we introduce a single photon counting hybrid pixel detector capable of detecting X-ray energies as low as 550 eV, utilizing the internal amplification of Low Gain Avalanche Diode (LGAD) sensors. This detector is thoroughly characterized in terms of Signal-to-Noise Ratio and Detective Quantum Efficiency. We demonstrate its capabilities through ptychographic imaging at MAX IV 4th-generation synchrotron light source at the Fe L 3 -edge (707 eV), showcasing the enhanced detection performance of the system. This development sets a benchmark for soft X-ray applications at synchrotrons, paving the way for significant advancements in imaging and analysis at lower photon energies. The internal amplification of Low-Gain Avalanche Diode sensors can enhance the signal-to-noise ratio, improving the detection of low-energy X-rays. In this work, the authors demonstrate a single photon counting hybrid pixel detector detecting X-ray energies down to 550 eV, and test it in ptychographic imaging at the Fe L 3 -edge.

Antiferromagnets hosting real-space topological textures are promising platforms to model fundamental ultrafast phenomena and explore spintronics. However, they have only been epitaxially fabricated on specific symmetry-matched substrates, thereby preserving their intrinsic magneto-crystalline order. This curtails their integration with dissimilar supports, restricting the scope of fundamental and applied investigations. Here we circumvent this limitation by designing detachable crystalline antiferromagnetic nanomembranes of α-Fe 2 O 3 . First, we show—via transmission-based antiferromagnetic vector mapping—that flat nanomembranes host a spin-reorientation transition and rich topological phenomenology. Second, we exploit their extreme flexibility to demonstrate the reconfiguration of antiferromagnetic states across three-dimensional membrane folds resulting from flexure-induced strains. Finally, we combine these developments using a controlled manipulator to realize the strain-driven non-thermal generation of topological textures at room temperature. The integration of such free-standing antiferromagnetic layers with flat/curved nanostructures could enable spin texture designs via magnetoelastic/geometric effects in the quasi-static and dynamical regimes, opening new explorations into curvilinear antiferromagnetism and unconventional computing. Topological antiferromagnetic states are generated and spatially reconfigured in free-standing crystalline membranes of haematite through strain design.

Neutron imaging was employed to track the uptake of Gd 3 + ions by the sub 2 nm micropores of charged activated carbon cloth electrodes from an aqueous Gd(NO 3 ) 3  solution. The transmitted neutron intensity evinces the persistent presence of Gd 3 + in the micropores during the discharge cycle, which is caused by the adsorption of oppositely charged ions. The charge efficiency of the activated carbon cloth system was determined by direct comparison with the imaged Gd 3 + concentration changes, with which the influence of ion swapping and resistive losses on capacitive deionization cells can be ascertained.

Hybrid pixel detectors have become indispensable at synchrotron and X-ray free-electron laser facilities thanks to their large dynamic range, high frame rate, low noise, and large area. However, at energies below 3 keV, the detector performance is often limited because of the poor quantum efficiency of the sensor and the difficulty in achieving single-photon resolution due to the low signal-to-noise ratio. In this paper, we address the quantum efficiency of silicon sensors by refining the design of the entrance window, mainly by passivating the silicon surface and optimizing the dopant profile of the n+ region. We present the measurement of the quantum efficiency in the soft X-ray energy range for silicon sensors with several process variations in the fabrication of planar sensors with thin entrance windows. The quantum efficiency for 250 eV photons is increased from almost 0.5% for a standard sensor to up to 62% as a consequence of these developments, comparable to the quantum efficiency of backside-illuminated scientific CMOS sensors. Finally, we discuss the influence of the various process parameters on quantum efficiency and present a strategy for further improvement.

Soft X-ray experiments at synchrotron light sources are essential for a wide range of research fields. However, commercially available detectors for this energy range often cannot deliver the necessary combination of quantum efficiency, signal-to-noise ratio, dynamic range, speed, and radiation hardness within a single system. While hybrid detectors have addressed these challenges effectively in the hard X-ray regime, specifically with single photon counting pixel detectors extensively used in high-performance synchrotron applications, similar solutions are desired for energies below 2 keV. In this work, we introduce the first single-photon-counting hybrid pixel detector capable of detecting X-ray energies as low as 550 eV, utilizing the internal amplification of Low-Gain Avalanche Diode (LGAD) sensors. This detector is thoroughly characterized in terms of Signal-to-Noise Ratio and Detective Quantum Efficiency. We demonstrate its capabilities through ptychographic imaging at MAX IV 4th generation synchrotron light source at the Fe L\\(_3\\)-edge (707 eV), showcasing the enhanced detection performance of the system. This development sets a new benchmark for soft X-ray applications at synchrotrons, paving the way for significant advancements in imaging and analysis at lower photon energies.

Understanding the magnetic and ferroelectric ordering of magnetoelectric multiferroic materials at the nanoscale necessitates a versatile imaging method with high spatial resolution. Here, soft X-ray ptychography is employed to simultaneously image the ferroelectric and antiferromagnetic domains in an 80 nm thin freestanding film of the room-temperature multiferroic BiFeO\\(_3\\) (BFO). The antiferromagnetic spin cycloid of period 64 nm is resolved by reconstructing the corresponding resonant elastic X-ray scattering in real space and visualized together with mosaic-like ferroelectric domains in a linear dichroic contrast image at the Fe L\\(_3\\) edge. The measurements reveal a near perfect coupling between the antiferromagnetic and ferroelectric ordering by which the propagation direction of the spin cycloid is locked orthogonally to the ferroelectric polarization. In addition, the study evinces both a preference for in-plane propagation of the spin cycloid and changes of the ferroelectric polarization by 71{\\deg} between multiferroic domains in the epitaxial strain-free, freestanding BFO film. The results provide a direct visualization of the strong magnetoelectric coupling in BFO and of its fine multiferroic domain structure, emphasizing the potential of ptychographic imaging for the study of multiferroics and non-collinear magnetic materials with soft X-rays.

The dynamics of domain walls in a square of permalloy (Ni\\(_{81}\\)Fe\\(_{19}\\); Py) upon excitation with an oscillating magnetic field of 4 mT amplitude were recorded by pump-probe ptychography with X-ray magnetic circular dichroism (XMCD) at the Ni L\\(_3\\)-edge. The 2.5 \\(\\mu\\)m Py square of 160 nm thickness forms a vortex flux-closure pattern with domain walls that fall into alternating out-of-plane magnetization states due to the interplay of in-plane shape and growth-induced perpendicular anisotropies. Dynamic modes of the domain wall structure were excitable along with the vortex core gyration with frequencies of 500 MHz and 1 GHz. Micromagnetic simulations served to corroborate the imaged domain wall motion.

Time-resolved pump-probe soft X-ray ptychography and Scanning Transmission X-ray Microscopy (STXM) were employed to study the magnetic domain wall dynamics in microstructures of permalloy (Ni\\(_81\\)Fe\\(_19\\); Py) with a weak growth-induced perpendicular magnetic anisotropy. The X-ray magnetic circular dichroism (XMCD) images of a micrometer-sized Py square (160 nm thickness) and an elliptical disk (80 nm thickness) show flux-closure patterns with domain walls that fall into alternating out-of-plane (OOP) magnetization states precipitated by the perpendicular anisotropy, which is a precursor of the nucleation of stripe domains at higher thicknesses. An oscillating magnetic field at frequencies from tens of MHz to GHz and up to 4 mT magnitude excited dynamic modes in the domain walls along with the vortex core gyration. The domain wall dynamics include the translation of inversion points of the OOP magnetization and nucleation of one-dimensional spin waves.

Soft x-ray ptychography is becoming a key synchrotron microscopy technique in the fields of condensed matter physics, chemistry, and environmental and life sciences. Its attractiveness across broad disciplinary fields is owed to the favorable combination of high spatial resolution and strong contrast mechanisms. The SOft X-ray Ptychography Highly Integrated Endstation (SOPHIE) at the Swiss Light Source (SLS) was developed to accommodate soft x-ray ptychography experiments requiring high spatial resolution, in addition to high chemical and ferroic sensitivities. An introduction to soft x-ray ptychography with SOPHIE aimed at prospective users is provided. Furthermore, an overview of the instrumentation of SOPHIE is given along with an example of the imaging capabilities, which demonstrate the achievement of a sub-10 nm spatial resolution at a photon energy of 706 eV.

Antiferromagnetic materials are promising platforms for the development of ultra-fast spintronics and magnonics due to their robust magnetism, high-frequency relativistic dynamics, low-loss transport, and the ability to support topological textures. However, achieving deterministic control over antiferromagnetic order in thin films is a major challenge, due to the formation of multi-domain states stabilised by competing magnetic and destressing interactions. Thus, the successful implementation of antiferromagnetic materials necessitates careful engineering of their anisotropy. Here, we demonstrate strain-based robust control over multiple antiferromagnetic anisotropies and nanoscale domains in the promising spintronic candidate a-Fe2O3, at room temperature. By applying isotropic and anisotropic in-plane strains across a broad temperature-strain phase space, we systematically tune the interplay between magneto-crystalline and magneto-elastic interactions. We discover that strain-driven control steers the system towards an aligned antiferromagnetic state, whilst preserving topological spin textures, such as merons, antimerons and bimerons. We directly map the nanoscale antiferromagnetic order using linear dichroic scanning transmission X-ray microscopy integrated with in situ strain and temperature control. A Landau model and micromagnetic simulations reveal how strain reshapes the magnetic energy landscape. These findings suggest that strain could serve as a versatile control mechanism to reconfigure equilibrium or dynamic antiferromagnetic states on demand in a-Fe2O3, paving the way for next-generation spintronic and magnonic devices.