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Antiferromagnets have large potential for ultrafast coherent switching of magnetic order with minimum heat dissipation. In materials such as Mn 2 Au and CuMnAs, electric rather than magnetic fields may control antiferromagnetic order by Néel spin-orbit torques (NSOTs). However, these torques have not yet been observed on ultrafast time scales. Here, we excite Mn 2 Au thin films with phase-locked single-cycle terahertz electromagnetic pulses and monitor the spin response with femtosecond magneto-optic probes. We observe signals whose symmetry, dynamics, terahertz-field scaling and dependence on sample structure are fully consistent with a uniform in-plane antiferromagnetic magnon driven by field-like terahertz NSOTs with a torkance of (150 ± 50) cm 2 A −1 s −1 . At incident terahertz electric fields above 500 kV cm −1 , we find pronounced nonlinear dynamics with massive Néel-vector deflections by as much as 30°. Our data are in excellent agreement with a micromagnetic model. It indicates that fully coherent Néel-vector switching by 90° within 1 ps is within close reach. Néel spin-orbit torques can occur in antiferromagnets with broken inversion symmetry, such as Mn 2 Au, and have garnered significant interest recently, as they allow for the electrical control of the antiferromagnetic ordering. Here, Behovits et al. apply intense terahertz electric fields to Mn 2 Au and observe the deflection of the Néel vector on ultrafast time scales due to Néel spin-orbit torques.

Current pulse driven Néel vector rotation in metallic antiferromagnets is one of the most promising concepts in antiferromagnetic spintronics. We show microscopically that the Néel vector of epitaxial thin films of the prototypical compound Mn 2 Au can be reoriented reversibly in the complete area of cross shaped device structures using single current pulses. The resulting domain pattern with aligned staggered magnetization is long term stable enabling memory applications. We achieve this switching with low heating of ≈20 K, which is promising regarding fast and efficient devices without the need for thermal activation. Current polarity dependent reversible domain wall motion demonstrates a Néel spin-orbit torque acting on the domain walls. Antiferromagnets have an inbuilt resilience to external magnetic fields and intrinsically fast dynamics, properties that have garnered interest in the hope that they could be used for antiferromagnet memories. Central to this are Neel spin-orbit torques, which can switch the individual sublattices of the antiferromagnet. Here, Reimers et al demonstrate complete and reversible current induced switching of the Neel vector in Mn 2 Au.

Imaging energy filters in photoelectron microscopes and momentum microscopes use spherical fields with deflection angles of 90°, 180° and even 2 × 180°. These instruments are optimized for high energy resolution, and exhibit image aberrations when operated in high transmission mode at medium energy resolution. Here, a new approach is presented for bandpass‐filtered imaging in real or reciprocal space using an electrostatic dodecapole with an asymmetric electrode array. In addition to energy‐dispersive beam deflection, this multipole allows aberration correction up to the third order. Here, its use is described as a bandpass prefilter in a time‐of‐flight momentum microscope at the hard X‐ray beamline P22 of PETRA III. The entire instrument is housed in a straight vacuum tube because the deflection angle is only 4° and the beam displacement in the filter is only ∼8 mm. The multipole is framed by transfer lenses in the entrance and exit branches. Two sets of 16 different‐sized entrance and exit apertures on piezomotor‐driven mounts allow selection of the desired bandpass. For pass energies between 100 and 1400 eV and slit widths between 0.5 and 4 mm, the transmitted kinetic energy intervals are between 10 eV and a few hundred electronvolts (full width at half‐maximum). The filter eliminates all higher or lower energy signals outside the selected bandpass, significantly improving the signal‐to‐background ratio in the time‐of‐flight analyzer. A compact bandpass prefilter eliminates electrons with energies above or below the desired range and can correct image aberrations up to the third order before the beam enters a time‐of‐flight analyzer. Here, the imaging performance of the filter is demonstrated for two key applications of high‐energy momentum microscopes: full‐field core‐level photoelectron diffraction and mapping of bulk valence bands.

The aluminum production is one of the most energy-intensive processes of modern industry. The paper describes an attempt to obtain aluminum by electrolysis according to the Hall-Herout’s process without utilization of the industrial electric power but due to the cheap renewable environmentally friendly solar energy using. In this version, the electrolysis cell heating is performed by a concentrator of solar radiation while the electrolysis process is carried out with the direct electric current from a solar battery. It is shown that the Hall-Heroult’s process can be carried out by the solar energy exclusively. The proposed approach is a some contribution to development of alternative energy industry, in particular in its using in the classical metallurgy processes.

Current pulse driven Néel vector rotation in metallic antiferromagnets is one of the most promising concepts in antiferromagnetic spintronics. We show microscopically that the Néel vector of epitaxial thin films of the prototypical compound Mn Au can be reoriented reversibly in the complete area of cross shaped device structures using single current pulses. The resulting domain pattern with aligned staggered magnetization is long term stable enabling memory applications. We achieve this switching with low heating of ≈20 K, which is promising regarding fast and efficient devices without the need for thermal activation. Current polarity dependent reversible domain wall motion demonstrates a Néel spin-orbit torque acting on the domain walls.

Imaging energy filters in photoelectron microscopes and momentum microscopes use spherical fields with deflection angles of 90{\\deg}, 180{\\deg}, and even 2 x 180{\\deg}. These instruments are optimized for high energy resolution, but exhibit image aberrations when operated in high transmission mode at medium energy resolution. Here we present a new approach for bandpass-filtered imaging in real or reciprocal space using an electrostatic dodecapole with an asymmetric electrode array. In addition to energy-dispersive beam deflection, this multipole allows aberration correction up to the 3rd order. Here we describe its use as a bandpass prefilter in a time-of-flight momentum microscope at the hard X-ray beamline P22 of PETRA III. The entire instrument is housed in a straight vacuum tube because the deflection angle is only 4{\\deg} and the beam displacement in the filter is only 8 mm. The multipole is framed by transfer lenses in the entrance and exit branches. Two sets of 16 different sized entrance and exit apertures on piezomotor driven mounts allow selection of the desired bandpass. For pass energies between 100 and 1400 eV and slit widths between 0.5 and 4 mm the transmitted kinetic energy intervals are between 10 eV and a few hundred eV (FWHM). The filter eliminates all higher or lower energy signals outside the selected bandpass, significantly improving the signal-to-background ratio in the ToF analyzer.

This study uses angle-resolved photoemission spectroscopy to examine the low-temperature electronic structure of Cs(V\\(_{0.95}\\)Nb\\(_{0.05}\\))\\(_3\\)Sb\\(_5\\), demonstrating that partially substituting V atoms with isoelectronic Nb atoms results in \\blue{an increase of the band width} and enhanced gap opening at the Dirac-like crossings due to the resulting chemical pressure. This increases the magnetic circular dichroism signal in the angular distribution (MCDAD) compared to CsV\\(_3\\)Sb\\(_5\\), enabling detailed analysis of magnetic circular dichroism in several bands near the Fermi level. These results \\blue{substantiate} the predicted coupling of orbital magnetic moments to three van Hove singularities near the Fermi level at M points. Previous studies have observed that Nb doping \\blue{lowers the charge density transition temperature} and increases the critical temperature for superconductivity. This article demonstrates that Nb doping concomitantly increases the magnetic circular dichroism signal attributed to orbital moments.

Imaging energy filters in photoelectron microscopes and momentum microscopes employ spherical fields with deflection angles of 90{\\deg}, 180{\\deg} and even 2 x 180{\\deg}. These instruments are optimized for high energy resolution, yet they come along with image aberrations when they are operated in high transmission mode with medium energy resolution. Here we present a new approach for bandpass-filtered imaging in real or reciprocal space, using an asymmetric electrostatic dodecapole. This multipole enables energy-dispersive beam deflection and correction of image aberrations up to the 3rd order. Owing to a deflection angle of only 4{\\deg}, the total beam displacement in the filter is just ~10 mm. Hence, the entire instrument is compact and just requires a straight vacuum tube. The multipole is framed by transfer lenses in the entrance and exit branch. Two sets of 16 entrance and exit apertures with different sizes on piezomotor-driven holders allow selecting the desired resolution. The combination of apertures and dodecapole acts as a bandpass pre-selector in a high-energy time-of-flight momentum microscope at the hard X-ray beamline P22 at PETRA-III (DESY, Hamburg). At pass energies between 400 and 600 eV it transmits electrons with kinetic energies in the range of 20-40 eV and thus effectively eliminates unwanted intensity from higher-energy electrons in the ToF analyzer. At low pass energies, the instrument allows energy-filtered imaging without subsequent ToF analysis. In a laboratory experiment the 4{\\deg} prototype reached < 500 meV resolution, which is sufficient for fast survey studies in the X-ray range.

Hard X-ray angle-resolved photoemission spectroscopy reveals significant alterations in the valence band states of EuPd\\(_2\\)Si\\(_2\\) at a temperature \\(T_V\\), where the Eu ions undergo a temperature-induced valence crossover from a magnetic Eu\\(^{2+}\\) state to a low-temperature valence-fluctuating state. The introduction of small amounts of Au on Pd lattice sites and Ge on Si sites, respectively, results in a decrease in \\(T_V\\) and the emergence of an antiferromagnetic state at low temperatures without valence fluctuations. It has been proposed that the boundary between AFM order and valence crossover represents a first-order phase transition associated with a specific type of second-order critical end point. In this scenario, strong coupling effects between fluctuating charge, spin, and lattice degrees of freedom are to be expected. In the case of EuPd\\(_2\\)(Si\\(_{1-x}\\)Ge\\(_x\\))\\(_2\\) with x=0.13, which is situated close to the critical end point, a splitting of conduction band states and the emergence of flat bands with one-dimensional character have been observed. A comparison with ab initio theory demonstrates a high degree of correlation with experimental findings, particularly in regard to the bands situated in proximity to the critical end point.

A new type of objective lens has recently been proposed for use in X-ray photoemission electron microscopes (XPEEMs) and momentum microscopes. Adding a ring electrode concentric with the extractor allows the field in the gap between the sample and the extractor to be shaped. Forming a lens field in this gap reduces the field strength at the sample by up to an order of magnitude. This mitigates the risk of field emission, particularly for cleaved samples with sharp edges. A retarding field can redirect all slow electrons, thus eliminating the primary contribution to the space-charge interaction. Here we present the first experimental investigation of the new lens, examining its performance at photon energies ranging from the extreme ultraviolet produced by a high-harmonic generation (HHG)-based source to soft and hard X-rays at two synchrotron facilities. The gap lens in a region without electrodes enables large working distances up to 23 mm. Reduced aberrations allow for larger fields of view in both k-space and real-space imaging, with resolutions comparable to those of conventional cathode lenses. However, field strengths are an order of magnitude smaller. The zero-field mode enables the study of 3D structured objects and is therefore beneficial for small cleaved samples as well as for operando devices involving top electrodes. The repeller mode reduces space-charge effects, but results in a smaller k-field diameter. This reduction ranges from 10% at hard X-ray energies to 50% in the XUV range. The usable energy interval is also reduced by a factor of two. In time-of-flight XPEEM mode the raw data show a resolution of 250 nm, which can be improved to better than 100 nm through data processing.