ABSTRACT With the establishment of two‐photon polymerization in additive manufacturing, the precise fabrication of arbitrarily shaped 3D features has become possible on the microscopic and even on the nanometric scale. The unsurpassed design freedom of this technique enables wide‐ranging applications across multiple research areas, such as microfluidics, photonics, life science, and micro‐electromechanical systems. Herein, the fabrication of a tailor‐made microchannel plate (MCP) generated by 3D‐nanoprinting (3DN) based on two‐photon polymerization is explored. A workflow for the 3DN‐MCP scaffold fabrication and subsequent functionalization by atomic layer deposition is presented. First strategies for print time reduction are proposed that allow for a 65% faster scaffold production, currently at the cost of microchannel shape accuracy. For the proof‐of‐concept experiment, a picoampere current is supplied by a carbon‐nanotube‐based field emitter to the 3DN‐MCP. An amplification factor in the order of 10 2 is measured for the 3DN‐MCP, which can likely be enhanced by microchannel dimension adjustments and further tuning of the surface coatings’ electrical properties in the future. Based on this study, innovative 3DN‐MCP designs may be explored, as the developed 3DN processing route is not limited to the conventional microchannel shape of glass‐based MCPs.
ABSTRACT Metallic van der Waals magnets provide an unusually direct setting in which electronic structure, dimensionality, and magnetic order can be tuned within the same crystalline platform. Fe3GeTe2 is a benchmark itinerant van der Waals ferromagnet because its Curie temperature, perpendicular magnetic anisotropy, coercivity, and anomalous Hall response depend strongly on thickness, stoichiometry, electrostatic gating, and interlayer hybridization. Above‐room‐temperature ferromagnetism in the structurally related Fe3GaTe2 raises a central question: does Ga substitution act mainly through carrier doping, or does it produce a broader reconstruction of bonding, exchange, anisotropy, and defect chemistry? This Short Review compares Fe3GeTe2 and Fe3GaTe2 from the perspective of carrier and band‐structure control. Evidence from gating, photoemission, magnetotransport, magnetic imaging, quantum sensing, scalable growth, and first‐principles theory demonstrates that Fe‐derived states near the Fermi level are highly tunable and that modest electronic changes can produce large magnetic responses. However, the comparison cannot be reduced to a rigid‐band picture. Ga changes the nominal electron count while also modifying orbital hybridization, lattice geometry, magnetic anisotropy, and defect formation. The enhanced Curie temperature of Fe3GaTe2 is therefore interpreted as the result of coupled electronic and structural optimization, suggesting practical design principles for high‐temperature metallic van der Waals magnets.
ABSTRACT Properties of fluids in fuel gas systems (high pressure) and catalytic reactors (high temperature and pressure) are essential for their modeling but scarcely available. Liquid toluene and methylcyclohexane have been operando observed upon pressurization with hydrogen, methane, or ethane using Neutron Imaging (NI). Studied systems mimic phase separation in fuel gases, for which interfacial tension, Henry's law volatility constant, apparent molar volume, diffusion coefficient of dissolved methane and ethane are experimentally provided, interfacial tension is measured for systems with hydrogen. This uniquely extensive basis of coupled experimental quantities has been compared with their Molecular Dynamics (MD) model predictions. Moreover, predictions of quantities inaccessible using NI, such as self‐diffusion coefficients, partial molar volumes, enthalpies and entropies of dissolution, or parameters of the Lennard‐Jones potential shed light on liquids exposed to fuel gases at high pressures. The MD model generally predicts system properties emerging from intermolecular interactions and can thus be used beyond the temperature and pressure limitations of the validation experiment. Following this concept, previously inaccessible diffusion coefficients in model bulk fluids mimicking the catalytic (de)hydrogenation of toluene are provided. This paves the way to detailed modeling of catalytic conversions in this Liquid Organic Hydrogen Carrier system.
ABSTRACT Metallic van der Waals magnets provide an unusually direct setting in which electronic structure, dimensionality, and magnetic order can be tuned within the same crystalline platform. Fe 3 GeTe 2 is a benchmark itinerant van der Waals ferromagnet because its Curie temperature, perpendicular magnetic anisotropy, coercivity, and anomalous Hall response depend strongly on thickness, stoichiometry, electrostatic gating, and interlayer hybridization. Above‐room‐temperature ferromagnetism in the structurally related Fe 3 GaTe 2 raises a central question: does Ga substitution act mainly through carrier doping, or does it produce a broader reconstruction of bonding, exchange, anisotropy, and defect chemistry? This Short Review compares Fe 3 GeTe 2 and Fe 3 GaTe 2 from the perspective of carrier and band‐structure control. Evidence from gating, photoemission, magnetotransport, magnetic imaging, quantum sensing, scalable growth, and first‐principles theory demonstrates that Fe‐derived states near the Fermi level are highly tunable and that modest electronic changes can produce large magnetic responses. However, the comparison cannot be reduced to a rigid‐band picture. Ga changes the nominal electron count while also modifying orbital hybridization, lattice geometry, magnetic anisotropy, and defect formation. The enhanced Curie temperature of Fe 3 GaTe 2 is therefore interpreted as the result of coupled electronic and structural optimization, suggesting practical design principles for high‐temperature metallic van der Waals magnets.
ABSTRACT The successful activation (ionization) of dopants is essential for the operation of virtually all semiconductor devices to obtain the required doping polarity and charge carrier density. On the nanoscale, however, the established effects of quantum confinement and dielectric mismatch impede dopant activation. Here, the ionization energies of dopant atoms in ultrathin silicon films embedded in different dielectric environments are calculated. We demonstrate that a stack of interfacial SiO2 combined with a thin high‐k HfO2 gate dielectric provides for a significantly reduced dopant deactivation by dielectric mismatch. Moreover, beyond the established dopant deactivation mechanisms, this study incorporates the impact of the Nanoscale Electronic Structure Shift Induced by Anions at Surfaces (NESSIAS) as a phenomenon that has previously not been considered in this context. The analysis models the NESSIAS as an additional interface potential that decays exponentially from the Si/SiO2 interface on length scales of only 1.5 nm. Nevertheless, a reduced dopant ionization energy, especially in the center of the Si films, is observed even for 13 nm Si thickness. These findings highlight the critical role of NESSIAS as an interface effect that fundamentally alters the spatial dependence of the dopant ionization energy and thereby impacts the dopant properties in nanoscale Si‐devices.
