Three-terminal gating offers an effective strategy for modulating the electrical transport and metal-insulator transition (MIT) behavior of vanadium dioxide (VO2), while conventional SiO2-gated VO2 devices usually show limited gate tunability. Here, we demonstrate large low-voltage resistance modulation in VO2 nanobeams directly grown on SiO2/Si substrates. The direct-growth configuration establishes a distinct VO2/SiO2 interfacial configuration in a Si-compatible back-gated device geometry. At room temperature, the channel resistance is reduced by approximately 75% under a gate voltage of only 3 V, corresponding to an electric field of 0.1 MV cm−1. When the device is biased near the MIT temperature, the same gate voltage triggers a gate-assisted transition, leading to a current increase of more than two orders of magnitude and a resistance modulation above 99%. In contrast, transferred VO2 nanobeam devices exhibit negligible gate-induced modulation even under much higher gate voltages, supporting an important role of the direct-growth-enabled VO2/SiO2 interfacial configuration in the enhanced gate response. These findings suggest that interfacial engineering may provide an effective route for improving the gate tunability of SiO2-gated VO2 devices, with potential for low-voltage, Si-compatible correlated-oxide electronics.
We demonstrated solid-phase epitaxy of Co2Fe0.4Mn0.6Si (CFMS) full-Heusler alloy electrodes in (001)-textured MgO-based magnetic tunnel junctions (MTJs) fabricated on thermally oxidized Si substrates. Initially amorphous CFMS electrodes crystallized into a (001)-textured structure templated by the adjacent MgO barrier during ex situ annealing without the use of any crystalline seed layers. The corresponding single CFMS thin films exhibited the (002) superlattice reflection, indicating B2 ordering. The CFMS/MgO-based MTJs exhibited high tunnel magnetoresistance ratios of 154% at room temperature and 347% at 40 K. These results highlight solid-phase epitaxy as a simple and effective route for integrating Heusler alloy-based MTJs into practical spintronic devices.
The dramatic slowing down of liquids approaching the glass transition remains unresolved, partly because competing theoretical explanations are difficult to discriminate. Indeed, several mature, contrasting frameworks account for the main features of glassy phenomenology, making agreement with familiar observations a weak basis for identifying the microscopic mechanism responsible for the slowdown. Recent numerical advances are changing this situation in two complementary ways. Deep equilibration extends controlled equilibrium studies into regimes previously accessible only by extrapolation, allowing established predictions to be stress-tested over a broader dynamical range. At the same time, new numerical methods increasingly provide direct access to theory-specific quantities such as configurational entropy, static lengths, elastic properties, and local activation barriers. I discuss how these developments constrain thermodynamic, facilitation-based, elastic, and excitation-based descriptions. The emerging picture is not yet a unique theory, but a set of increasingly discriminating tests that can reveal where apparently successful laws cease to be universal and identify the microscopic ingredients that causally control the activation barrier.
Confining infrared light at the nanoscale with low losses is a central challenge in nanophotonics. Surface phonon polaritons in polar dielectrics offer a compelling solution, yet the available materials palette and fabrication routes remain largely limited to top-down lithography. Here, we demonstrate localized phonon-polariton resonances in colloidal calcium fluoride nanoparticles—to our knowledge, the first such observation in a chemically synthesized alkaline-earth fluoride—in the 8–14 THz range. We introduce an analytical model that quantitatively reproduces the far-infrared absorption spectra without requiring full electrodynamic simulations and use it to extract nanoparticle densities in good agreement with those derived from the nanoparticle geometry. Our results establish colloidal synthesis as a viable, scalable route to phonon-polaritonic resonators, broadening both the materials toolbox and the fabrication strategies available for far-infrared nanophotonics.
