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B20-CoSi is a newly discovered Weyl semimetal that crystallizes into a non-centrosymmetric crystal structure. However, the investigation of B20-CoSi has so far been focused on bulk materials, whereas the growth of thin films on technology-relevant substrates is a prerequisite for most practical applications. In this study, we have used millisecond-range flash-lamp annealing, a non-equilibrium solid-state reaction, to grow B20-CoSi thin films. By optimizing the annealing parameters, we were able to obtain thin films with a pure B20-CoSi phase. The magnetic and transport measurements indicate the appearance of the charge density wave and the chiral anomaly. Our work presents a promising method for preparing thin films of most binary B20 transition-metal silicides, which are candidates for topological Weyl semimetals.

The use of metal nanoparticles (NPs) as antimicrobial agents has become a promising alternative to the problem of antibiotic-resistant bacteria and other applications. Silver nanoparticles (AgNPs) are well-known as one of the most universal biocide compounds. However, selenium nanoparticles (SeNPs) recently gained more attention as effective antimicrobial agents. This study aims to investigate the antibacterial activity of SeNPs with different surface coatings (BSA-coated, chitosan-coated, and undefined coating) on the Gram-negative Stenotrophomonas bentonitica and the Gram-positive Lysinibacillus sphaericus in comparison to AgNPs. The tested NPs had similar properties, including shape (spheres), structure (amorphous), and size (50−90 nm), but differed in their surface charge. Chitosan SeNPs exhibited a positive surface charge, while the remaining NPs assayed had a negative surface charge. We have found that cell growth and viability of both bacteria were negatively affected in the presence of the NPs, as indicated by microcalorimetry and flow cytometry. Specifically, undefined coating SeNPs displayed the highest percentage values of dead cells for both bacteria (85−91%). An increase in reactive oxygen species (ROS) production was also detected. Chitosan-coated and undefined SeNPs caused the highest amount of ROS (299.7 and 289% over untreated controls) for S. bentonitica and L. sphaericus, respectively. Based on DNA degradation levels, undefined-SeNPs were found to be the most hazardous, causing nearly 80% DNA degradation. Finally, electron microscopy revealed the ability of the cells to transform the different SeNP types (amorphous) to crystalline SeNPs (trigonal/monoclinical Se), which could have environmentally positive implications for bioremediation purposes and provide a novel green method for the formation of crystalline SeNPs. The results obtained herein demonstrate the promising potential of SeNPs for their use in medicine as antimicrobial agents, and we propose S. bentonitica and L. sphaericus as candidates for new bioremediation strategies and NP synthesis with potential applications in many fields.

Chemoenzymatic cascades are an important tool for advanced synthesis in chemistry. However, these cascades are often limited due to the incompatibility issue between two distinct catalysts and reactions. To address this issue, we present a simple multistep one-pot platform, in which nanoparticle catalysts are prepared to allow chemo- and biocatalytic reactions performed sequentially in water and Pickering emulsions. The preparation of particle catalysts is accomplished in just two steps by polymer modifications and [RuCl2(pcymene)]2 coordination, while the benefits of using them for chemoenzymatic synthesis are multifaceted. They act not only as asymmetric catalysts for asymmetric transfer hydrogenation from acetophenone to 1-phenylethanol in water with up to 99 % conversion and 93 % ee, but also as an emulsifier to form stable Pickering emulsions. By the addition of Candida antarctica lipase B into the emulsions, the second-step reaction of enantioselective acylation was achieved with 38 % conversion and 99 % ee. Therefore, we successfully present a simple method to enable chemoenzymatic cascades by combining particle catalysts and enzymes in water and Pickering emulsions in a sequential fashion, which can be generalized for other cascade syntheses with different chemo- and biocatalysts in the future.

Layered van der Waals crystals host unique properties making them attractive for applications in nanoelectronics, optoelectronics, and sensing. The integration of two-dimensional materials with complementary metal-oxide-semiconductor (CMOS) technology requires controllable n- and p-type doping. In this work, we demonstrate the fabrication of vertical p-n heterojunctions made of p-type tin monoselenide (SnSe) and n-type tin diselenide (SnSe2). The p-n heterojunction is created in a single flake by the NH3-plasma-assisted phase transformation from SnSe2 to SnSe. We show that the transformation rate and crystal quality strongly depend on the plasma parameters like plasma power, temperature, partial pressure, NH3 flow, and duration of plasma treatment. With optimal plasma parameters, the full transformation of SnSe2 flakes to SnSe is achieved within a few seconds. The crystal quality and the topography of the fabricated SnSe-SnSe2 heterostructures are investigated using micro-Raman spectroscopy and cross-sectional transmission electron microscopy. The formation of a p-n junction is verified by current-voltage measurements.

Decentralized electrochemical production of hydrogen peroxide (H2O2) is an attractive alternative to the industrial anthraquinone process, the application of which is hindered by the lack of high-performance electrocatalysts in acidic media. Herein, a novel catalyst design strategy is reported to optimize the Pd sites in pure metallic aerogels by tuning their geometric environments and electronic structures. By increasing the Hg content in the Pd-Hg aerogels, the Pd-Pd coordination is gradually diminished, resulting in isolated, single-atom-like Pd motifs in the Pd2Hg5 aerogel. Further heterometal doping leads to a series of M-Pd2Hg5 aerogels with an unalterable geometric environment, allowing for sole investigation of the electronic effects. Combining theoretical and experimental analyses, a volcano relationship is obtained for the M-Pd2Hg5 aerogels, demonstrating an effective tunability of the electronic structure of the Pd active sites. The optimized Au-Pd2Hg5 aerogel exhibits an outstanding H2O2 selectivity of 92.8% as well as transferred electron numbers of ≈2.1 in the potential range of 0.0-0.4 VRHE. This work opens a door for designing metallic aerogel electrocatalysts for H2O2 production and highlights the importance of electronic effects in tuning electrocatalytic performances.

Most industrial processes are generating waste heat that can be converted into electrical energy with thermoelectric generators (TEGs). For efficient energy harvesting, it is necessary to significantly improve the properties like Seebeck coefficient, electrical and thermal conductivity of the thermoelectric materials in the TEGs. One promising approach are thermoelectric nanostructures to reduce the thermal conductivity while maintaining constant electrical conductivity and Seebeck coefficient. For that reason, this study investigated the possibility of preparing nanowires of the thermoelectric material iron antimonide (FeSb₂) on crystalline gallium arsenide GaAs(001) substrates with ion-induced surface nanopatterning. The GaAs(001) substrates were pre-patterned using 1 keV Ar⁺ ion irradiation. By using an ion source with a broad, unfocused ion beam at normal incidence, the patterned area can be scaled to nearly any size. The self-organized surface structure is formed by reverse epitaxy and is characterized by almost perfectly parallel-aligned ripples at the nanometer scale. For the fabrication of FeSb₂ nanowires, iron and antimony were successively deposited on the prepatterned GaAs substrates at grazing incidence and then annealed. They were characterized using transmission electron microscopy (TEM), in particular high-resolution TEM imaging for structure analysis and spectrum imaging analysis based on energy-dispersive X-ray spectroscopy for element characterization. With the presented fabrication method, FeSb₂ nanowires were produced successfully on GaAs(001) substrates with an ion-induced nanopatterned surface. The nanowires have a polycristalline structure and a cross-sectional area which is scalable up to 22×22nm². Due to the highly ordered nanostructure of the GaAs substrates, the nanowires have a length of several micrometer. These bottom-up nanofabrication based on ion-induced patterning can be a viable alternative to top-down procedures regarding to efficiency and costs.

Antiferromagnetic insulators are a prospective material science platform for magnonics, spin superfluidity, THz spintronics, and non-volatile data storage. A magnetomechanical coupling in antiferromagnets offers vast advantages in the control and manipulation of the primary order parameter yet remains largely unexplored both fundamentally and technologically. Here, we discover a new member in the family of flexoeffects in thin films of technologically relevant antiferromagnetic Cr2O3. We demonstrate that a gradient of mechanical strain can impact the magnetic phase transition resulting in the distribution of the N ́eel temperature along the thickness of a 50-nm-thick film and induces a sizable flexomagnetic coefficient of about 15 μb/nm2 originating from the inhomogeneous reduction of the antiferromagnetic order parameter. The antiferromagnetic ordering in inhomogeneously strained thin films of Cr2O3 can persist up to 100◦ C, rendering Cr2O3 relevant for industrial electronics applications. The presence of a strain gradient in thin films of Cr2O3 may therefore allow for the realization of reconfigurable antiferromagnetic racetracks, magnonic waveguides and magnon crystals. The presence of a strain gradient in ultrathin films of Cr2O3 enables new fundamental research directions on magnetomechanics and thermodynamics of antiferromagnetic solitons, spin waves and artificial spin ice systems in magnetic materials with continuously graded parameters.

Optical pump – Terahertz (THz) probe (OPTP) spectroscopy has proven efficacy for contactless probing of electronic transport in semiconductor NWs [1]. Particularly in III-V NWs, scattering rates of charge carriers, as well as their plasmonic resonances for typical doping levels, are located in the THz range. The analysis of the optical conductivity spectra using the localized surface plasmon model allows estimating the carrier lifetime and the carrier mobility. Here, OPTP spectroscopy is employed to study two unique phenomena in GaAs/(In,Al,Ga)As core/shell nanowires. First, it is demonstrated that the mobility of electrons in the hydrostaticallystrained GaAs core (owing to the lattice mismatch between the core and the shell [2]) exceeds the mobility in bulk GaAs by 30-50% [3]. The role of the various scattering mechanisms is analyzed as a function of strain and temperature. Depending on the density of NWs in the probed sample, some of them can form bundles or touch each other, leading to an inhomogeneous broadening of the plasmon resonance. We discuss the role of this effect and its impact on the estimation of carrier mobility [3, 4]. Second, we demonstrate a strong THz nonlinearity using single-cycle intense THz pulses with peak electric fields reaching up to 0.6 MV/cm. With the increase of the driving THz field, we observe a systematic redshift of the plasmon frequency, accompanied by a gradual suppression of the spectral weight. Remarkably, the spectral weight does not remain proportional to the square of the plasmon frequency when the driving electric field exceeds 0.4 MV/cm, indicating an onset of a spatially inhomogeneous carrier distribution across the NW. The observed behavior can be ascribed to nonlinear effects caused by the scattering of electrons from the Gamma- to L-valley occurring in the high electric field regime. However, in contrast to bulk semiconductors, this effect initially sets in at hot spots of the NW, where the local electric field is enhanced by the plasmonic resonance [5]. All in all, our findings provide important guidelines for the exploitation of nanowires in high-frequency electronics, but also underline the unique strengths of OPTP spectroscopy for the study of electronic transport in nanowires. [1] H. J. Joyce et al., Semicond. Sci. Technol. 31, 103003 (2016). [2] L. Balaghi et al., Nat. Commun. 10, 2793 (2019). [3] L. Balaghi et al., Nat. Commun. 12, 6642 (2021). [4] I. Fotev et al., Nanotechnology 30, 244004 (2019). [5] R. Rana et al., Nano Lett. 20, 3225 (2020).

Due to their self-supporting and nanoparticulate structure, metal aerogels have emerged as excellent electrocatalysts, especially in the light of the shift to renewable energy cycles. While a large number of synthesis parameters have already been studied in depth, only superficial attention has been paid to the solvent. In order to investigate the influence of this parameter with respect to the gelation time, crystallinity, morphology, or porosity of metal gels, AuxCuy aerogels were prepared in water and ethanol. It was shown that although gelation in water leads to highly porous gels (60 m2g-1), a CuO phase forms during this process. The undesired oxide could be selectively removed using a post-washing step with formic acid. In contrast, the solvent change to EtOH led to a halving of the gelation time and the suppression of Cu oxidation. Thus, pure Cu aerogels were synthesized in addition to various bimetallic Au3X (X = Ni, Fe, Co) gels. The faster gelation, caused by the lower permittivity of EtOH, led to the formation of thicker gel strands, which resulted in a lower porosity of the AuxCuy aerogels. The advantage given by the solvent choice simplifies the preparation of metal aerogels and provides deeper knowledge about their gelation.

Silicon oxide films are widely applied for their superior dielectric, chemical and mechanic properties as well as for their resistance against reactive chemicals. Simultaneously, there is an increasing number of applications which demand a low deposition temperature. In this work, we compare the material properties of SiOx layers deposited at ca. 70°C by atmospheric-pressure plasma jet deposition (PA) with those of SiO2 layers thermally grown or deposited by plasma-enhanced chemical vapour deposition. The films were deposited on silicon wafers and analysed using different analysis techniques. According to cross-sectional transmission electron microscopy and high-frequency capacitance-voltage measurements, the interface between the PA oxide and the Si substrate is smooth with no apparent defects and displays an electrically active interface defect density between 3.5-8.0×1012 cm-2 directly after deposition and below 2.0×1012 cm-2 after furnace annealing. Right after deposition, the PA oxide contains carbon and hydrogen in a concentration of several at%, and the SiO2 plasma polymer network comprises several active centres (residual charge, free radicals, non-saturated bonds). The most abundant configuration is the Si(-O)4 tetrahedron, followed by Si(-O)3 with similar intensity. This indicates that there are still dangling Si bonds or bonds terminated by hydroxyl or methyl groups. After furnace annealing, the formation of the SiO2 network is completed and the optical and electrical properties of the PA oxide converge to that of thermal oxide.

Thin films of the magnetoelectric insulator α-Cr2O3 are technologically relevant for energy-efficient magnetic memory devices controlled by electric fields. In contrast to single crystals, the quality of thin Cr2O3 films is usually compromised by the presence of point defects and their agglomerations at grain boundaries, putting into question their application potential. Here, we study the impact of the defect nanostructure including sparse small-volume defects and their complexes on the magnetic properties of Cr2O3 thin films. By tuning the deposition temperature, we tailor the type, size, and relative concentration of defects, which we then analyze based on positron annihilation spectroscopy complemented with local electron microscopy studies. The structural characterization is correlated with magnetotransport measurements and nitrogen vacancy microscopy of antiferromagnetic domain patterns. Defects pin antiferromagnetic domain walls and stabilize complex multidomain states with a typical domain size in the sub-micrometer range. Despite their influence on the domain configuration, we demonstrate that neither small open-volume defects nor grain boundaries in Cr2O3 thin films affect the Néel temperature in a broad range of deposition parameters. Our results pave the way towards the realization of spin-orbitronic devices where magnetic domain patterns can be tailored based on defect nanostructures without affecting their operation temperature.

Transition metal oxides have been extensively explored as novel catalysts for designing electrochemical sensors, but the underlying structure-activity relationship remains poorly understood. Herein, we explore a diverse chemical range of La1-xSrxFeO3 perovskite oxides by evaluating their electrochemical sensing activity toward heavy metals and by determining their electronic structures using density functional theory. We find that tuning perovskite chemistry plays an important role in determining the electrochemical activities and sensitivities, as well as the valence states of Fe. By combining experimental and theoretical analyses, a linear relationship between the Fe−O covalency and the electrochemical activity and sensitivity has been obtained, where LaFeO3 exhibits the highest activity of 109 mA cmoxide-2.Thus, the Fe−O covalency is proposed as a rational activity descriptor for the electrochemical sensing of heavy metals. A novel solid-state gelation method was further developed for the fabrication of perovskite oxide aerogels, based on which a highly efficient electrochemical sensor was constructed with a high sensitivity of 87.06 μM μA-1 and a low detection limit of 1.7 nM. This work unlocks an effective parameter, that is, Fe−O covalency, for rationally designing Fe-based oxides and deepening the understanding of fundamental parameters to develop highly efficient sensing platforms.

This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative.

ZusammenfassungDie interventionelle Emphysemtherapie bietet ein breites Spektrum an chirurgischen und endoskopischen Optionen zur Behandlung von Patienten mit fortgeschrittenem Lungenemphysem. Zur Sicherstellung der Behandlungsqualität ist eine interdisziplinäre Zusammenarbeit von Pneumologie, Thoraxchirurgie und bildgebenden Disziplinen in der Auswahl, Therapie und Nachsorge von Emphysem-Patienten erforderlich. Das vorliegende Positionspapier beschreibt erforderliche Struktur- und Qualitätsvoraussetzungen von Behandlungszentren.

Clay formations are potential host rocks for the long-term storage of high-level radioactive waste in a deep geological repository. Bentonites are supposed to serve as backfill material, not only for a final disposal site in clay formations but also in crystalline rock. For a long-term safety assessment, various aspects must be taken into account. Besides geological, geochemical, and geophysical considerations, also naturally occurring microorganisms play a crucial part in the environment of such a repository. In the event of a worst-case scenario, if water enters the disposal site, they can interact with the radionuclides and change for example the chemical speciation or the oxidation state (Lloyd et al., 2002). Desulfosporosinus spp. are an important representative of anaerobic, sulfate-reducing microorganisms, which are present in clay formations as well as in bentonites. Various studies show that they are playing a major role in the microbial communities of these surroundings (Bagnoud et al., 2016; Matschiavelli et al., 2019). A closely related microorganism to the isolated species is Desulfosporosinus hippei DSM 8344, which was originally found in permafrost soil (Vatsurina et al., 2008). This bacterium was used to investigate its interactions with uranium(VI) especially regarding the reduction to the less mobile uranium(IV). Time-dependent reduction experiments in artificial Opalinus Clay pore water (Wersin et al., 2011) (100 µM uranium(VI), pH 5.5) showed the removal of about 80% of the uranium(VI) from the supernatants within 48 h. Corresponding UV/Vis measurements of the dissolved cell pellets exhibit an increasing proportion of uranium(IV) in the cell-bound uranium. Calculations with the inclusion of extinction coefficients lead to a ratio of 39% uranium(IV) after one week. Therefore, a combined sorption-reduction process is a possible interaction mechanism. Time-resolved laser-induced luminescence spectroscopy verifies the presence of two uranium(VI) species in the supernatant. A comparison with reference spectra leads to an assignment to a uranyl(VI) lactate and a uranyl(VI) carbonate complex. The species distribution shows a decrease of the proportion of the lactate species with time, whereas the proportion of the carbonate species remains almost constant. Uranium aggregates are formed on the cell surface during the process, as determined by transmission electron microscopy (TEM). Furthermore, uranium occurs inside and outside the cells as well as uranium-containing vesicles. These findings help to close existing gaps in a comprehensive safeguards concept for a repository for high-level radioactive waste in clay rock. Moreover, this study provides new insights into the interactions of sulfate-reducing microorganisms with uranium(VI). References Bagnoud, A., Chourey, K., Hettich, R. L., De Bruijn, I., Andersson, A. F., Leupin, O. X., Schwyn, B., and Bernier-Latmani, R.: Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock, Nat. Commun., 7, 1-10, 2016. Lloyd, J. R. and Macaskie, L. E.: Biochemical basis of microbe-radionuclide interactions, in: Interactions of Microorganisms with Radionuclides, edited by: Keith-Roach, M. J. and Livens, F. R., Elsevier, 313-381, 2002. Matschiavelli, N., Kluge, S., Podlech, C., Standhaft, D., Grathoff, G., Ikeda-Ohno, A., Warr, L. N., Chukharkina, A., Arnold, T., and Cherkouk, A.: The year-long development of microorganisms in uncompacted Bavarian bentonite slurries at 30 °C and 60 °C, Environ. Sci. Technol., 53, 10514-10524, 2019. Vatsurina, A., Badrutdinova, D., Schumann, P., Spring, S., Vainshtein, M.: Desulfosporosinus hippei sp. nov., a mesophilic sulfate-reducing bacterium isolated from permafrost, Int. J. Syst. Evol. Microbiol., 58, 1228-1232, 2008. Wersin, P., Leupin, O. X., Mettler, S., Gaucher, E. C., Mäder, U., De Cannière, P., Vinsot, A., Gäbler, H. E., Kunimaro, T., Kiho, K., Eichinger, L.: Biogeochemical processes in a clay formation in situ experiment: Part A - Overview, experimental design and water data of an experiment in the Opalinus Clay at the Mont Terri Underground Research Laboratory, Switzerland, Appl. Geochemistry, 26, 931-953, 2011.

Armed with merits of the metals (e.g., electrical conductivity, catalytic activity, and plasmonic properties) and aerogels (e.g., monolithic structure, porous network, and large specific surface area), metal aerogels (MAs) have stood out as a new class of porous materials in the last decade. With unparalleled potential in electrocatalysis, plasmonics, and sensing, they are envisaged to revolutionize the energy- and detection-related application fields. However, MA development is severely retarded by the lack of a sufficient material basis. Suffering from the ambiguous understanding of formation mechanisms, big challenges remain for tailoring MAs for task-specific applications. By surveying state-of-the-art developments, this review strives to summarize design principles and arouse interest in broad scientific communities. Moreover, critical challenges and opportunities are highlighted to provide a research roadmap for this young yet promising field.

The anisotropy in semiconductor nanoplatelets (NPLs) is reflected in the anisotropy of their crystal structure and organic ligand shell, which can be used for creating new semiconductor heterostructures. This work demonstrates the synthesis of core/shell NPLs containing zero-dimensional (0D) CdxHg1−xSe domains embedded in CdSe NPLs via cation exchange. The strategy is based on the different accessibility of definite regions of the NPLs for incoming cations upon time-limited reaction conditions. The obtained heterostructures were successfully overcoated with a CdyZn1−yS shell preserving their two-dimensional (2D) morphology. The NPLs exhibit bright photoluminescence in the range of 700-1100 nm with quantum yields up to 55%, thus making them a prospective material for light-emitting applications in the near-infrared spectral range.

B20-type FeGe is one of the noncentrosymmetric materials hosting magnetic skymions. In this work, we have prepared B20-type FeGe films by pulsed laser melting of metal Fe deposited on Ge(100). The formation of the B20 phase is confirmed by X-ray diffraction. The FeGe samples show a superparamagnetic behaviour and their blocking temperatures increase with increasing the pulsed laser energy density. We conclude that this phenomenon is due to the increased grain size of the B20-type FeGe with increasing laser energy density. The presented method can be used to obtain different B20-type transition metal germanides and silicides, which can be magnetic skyrmion-hosting materials for spintronics.

The research on surface-enhanced Raman scattering (SERS) continuously draws wide attention because of its high detection sensitivity. However, the commonly investigated 2D SERS substrates cannot fully utilize the 3D active focal volume and require a tight focus on the correct plane, retarding signal enhancement and flexible use. Here, self-supported gold aerogels of centimeter-dimension with tunable ligament sizes are designed as 3D SERS substrates, featuring hot spots throughout the entire network. Unveiling a universal ligament-size-effect, the optimized gold aerogel showcases much larger enhancement factors compared to a 8 nm Au film toward dyes, pesticides, and carcinogens (up to 109). Aside from an excellent reusability and an exceptional stability (> 1 month), an outstanding misfocus tolerance (>300 μm along the z-axis) is also demonstrated for such aerogel-based SERS substrates for multiplex detection. This work may expand the application scope of metal aerogels and lay the foundation for designing next-generation 3D SERS substrates.

The formation of nanopores by highly charged ion impacts on freestanding fluorine-functionalized graphene is demonstrated. The process is driven by potential sputtering, which becomes active by changing the semi-metallic properties of graphene into a strongly insulating state by fluorination. The interaction of fluorographene with highly charged ions is also studied in terms of charge exchange and kinetic energy loss. A higher number of captured electrons and a larger kinetic energy loss than in pristine graphene are observed, which can be well explained by an increase in the ion's neutralization length and in the atomic areal density of the target, respectively. Using a computer code based on a time-dependent scattering potential model, a connection between the efficiency of charge exchange and the fluorine coverage is revealed. Our results suggest a competition of two distinct nanostructure formation processes leading either to pore formation or fluorine desorption.

B20-type transition-metal silicides or germanides are noncentrosymmetric materials hosting magnetic skyrmions, which are promising information carriers in spintronic devices. The prerequisite is the preparation of thin films on technology-relevant substrates with magnetic skyrmions stabilized at a broad temperature and magnetic-field working window. The canonical example is the B20-MnSi film grown on Si substrates. However, the as-yet unavoidable contamination with MnSi1.7 occurs due to the lower nucleation temperature of this phase. In this work, we report a simple and efficient method to overcome this problem and prepare single-phase MnSi films on Si substrates. It is based on the millisecond reaction between metallic Mn and Si using flash lamp annealing (FLA). By controlling the FLA energy density, we can grow single-phase MnSi or MnSi1.7 or their mixture at will. Compared with bulk MnSi the prepared MnSi films show an increased Curie temperature of up to 41 K. In particular, the magnetic skyrmions are stable over a much wider temperature and magnetic-field range than reported previously. Our results constitute a novel phase selection approach for alloys and can help enhance specific functional properties such as enhancing the stability of magnetic skyrmions.

Magnetic skyrmions have been suggested as information carriers for future spintronic devices. As the first material with experimentally confirmed skyrmions, B20-type MnSi has the research focus for decades. Although B20-MnSi films have been successfully grown on Si(111) substrates, there is no report about B20-MnSi films on Si(100) substrates, which would be more preferred for practical applications. In this letter, we present the first preparation of B20-MnSi on Si(100) substrates. It is realized by sub-second solid-state reaction between Mn and Si via flash-lamp annealing at ambient pressure. The regrown layer shows an enhanced Curie temperature of 43 K compared with bulk B20-MnSi. The magnetic skyrmion signature is proved in our films by magnetic and transport measurements. The millisecond-range flash annealing provides a promising avenue for the fabrication of Si-based skyrmionic devices.

We have studied thermally driven magnon spin transport (spin Seebeck e_ect, SSE) in heterostructures of antiferromagnetic Cr2O3 and Pt at low temperatures. Monitoring the amplitude of the local and nonlocal SSE signals as a function of temperature, we found that both decrease with increasing temperature and disappear above 100 K and 20 K, respectively. Additionally, both SSE signals show a tendency to saturate at low temperatures. The nonlocal SSE signal decays exponentially for intermediate injector-detector separation, consistent with magnon spin current transport in the relaxation regime. We estimate the magnon relaxation length of our Cr2O3 films to be around 500 nm at 3 K. This short magnon relaxation length along with the strong temperature dependence of the SSE signal indicates that temperature-dependent inelastic magnon scattering processes play an important role in the intermediate range magnon transport. Our observation is relevant to low-dissipation antiferromagnetic magnon memory and logic devices involving thermal magnon generation and transport.

In this study, we investigated the interaction of U(VI) and Eu(III) with Brassica napus suspension plant cells as a model system. Concentration-dependent (0-200 µM) bioassociation experiments showed that more than 75% of U(VI) and Eu(III) were immobilized by the cells. In addition to this phenomenon, time-dependent studies for 1 to 72 h of exposure showed a multi-stage bioassociation process for cells that were exposed to 200 µM U(VI), where, after initial immobilization of U(VI) within 1 h of exposure, it was released back into culture medium starting within 24 h. A re-mobilization to this extent has not been previously observed. The MTT assay was used to correlate the bioassociation behavior of Eu and U with the cell vitality. Speciation studies by spectroscopy and in silico methods highlighted various U and Eu species over the course of exposure. We were able to observe a new U species, which emerged simultaneously with the re-mobilization of U back into solution, which we assume to be a U(VI) phosphate species. Thus, the interaction of U(VI) and Eu(III) with released plant metabolites could be concluded.

Lateral-channel dual-gate organic thin-film transistors have been used in pseudo complementary metal-oxide-semiconductor (CMOS) inverters to control switching voltage. However, their relatively long channel lengths, combined with the low charge carrier mobility of organic semiconductors, typically leads to slow inverter operation. Vertical-channel dual-gate organic thin-film transistors are a promising alternative because of their short channel lengths, but the lack of appropriate p- and n-type devices has limited the development of complementary inverter circuits. Here, we show that organic vertical n-channel permeable single- and dual-base transistors, and vertical p-channel permeable base transistors can be used to create integrated complementary inverters and ring oscillators. The vertical dual-base transistors enable switching voltage shift and gain enhancement. The inverters exhibit small switching time constants at 10 MHz, and the seven-stage complementary ring oscillators exhibit short signal propagation delays of 11 ns per stage at a supply voltage of 4 V.