Search for: All records

The properties of chalcogenide phase change materials have long attracted the scientific community due to a combination of state retention (i.e., memory) and a large contrast in electrical and optical properties between different solid phases. The last decade has witnessed a vast interest in utilizing this material family for optics and photonics, given their large refractive index modulation, nonvolatility—elusive in optics—and straightforward integration into photonic devices. Thus, designing new optical phase change materials (O-PCMs) and demonstrating high-performance applications have become fast-growing research topics. However, advances in O-PCMs have predominantly followed empirical device developments, driven by their promise in trending technological applications. Nonetheless, a growing interest in revealing their materials science intricacies is driving the much-needed effort toward a holistic understanding and codesign of O-PCMs, which is required to fill knowledge gaps, expand the materials library, and solve the most pressing device performance challenges. 

The static recrystallization and grain growth of a hybrid AZ31/Mg-0.6Gd (wt%) material fabricated by high pressure torsion (HPT) through 20 turns were explored after isochronal annealing at 150, 250, 350 and 450 ◦C for 1 h using electron backscatter diffraction, transmission electron microscopy and Vickers microhardness measurements. The results reveal heterogeneity in the grain size distributions of the AZ31 and Mg-0.6Gd regions after annealing at the lower temperatures of 150 and 250 ◦C leading to a clear AZ31/Mg-0.6Gd interfacial border. At the higher temperatures of 350 and 450 ◦C the AZ31/Mg-0.6Gd interfaces were not well-defined owing to the occurrence of grain growth. It is shown that grain growth is restricted in the AZ31 and Mg-0.6Gd regions due to the presence of stable nano-size Al8Mn5 particles and the precipitation of Mg17Al12 and Mg12Zn at 250 ◦C and of Mg5Gd and Mg12Gd phases at 350 and 450 ◦C. The distribution of the basal texture in both regions was strongly controlled by dynamic recrystallization, precipitation and grain growth. The values of the microhardness over the radial cross-sections of the hybrid discs decrease and become more uniform, in the range of ~35–66 Hv, with increasing annealing temperature. 

Abstract Visual-world eye-tracking has long been a useful tool for measuring young children’s real-time interpretation of words and sentences. Recently, researchers have extended this method to virtual platforms to reduce equipment costs and recruit more diverse participants. However, there is currently limited guidance on best practices, which require individual researchers to invent their own methodologies and may prevent broader adoption. Here, we present three broad approaches for implementing nine remote visual-world eye-tracking studies, and show that this method is highly feasible for assessing fine-grained language processing across populations of varying ages, clinical statuses, and socioeconomic status backgrounds. We outline strategic methods for conducting this research effectively, including strategies for experimental design, data collection, and data analysis given the variable conditions outside of a lab setting. We adopt four criteria for evaluating success for this method: 1) Minimal subject attrition relative to in-person studies, 2) Minimal track loss relative to conventional eye-tracking, 3) Conceptual replication of previous findings, and 4) Evidence of broadening participation. These case studies provide a thorough guide to future researchers looking to conduct remote eye-tracking research with developmental populations. Ultimately, we conclude that visual-world eye-tracking using internet-based methods is feasible for research with young children and may provide a relatively inexpensive option that can reach a broader, more diverse set of participants. 

Plasmoid instability accelerates reconnection in collisional plasmas by transforming a laminar reconnection layer into numerous plasmoids connected by secondary current sheets in two dimensions (2D) and by fostering self-generated turbulent reconnection in three dimensions (3D). In large-scale astrophysical and space systems, plasmoid instability likely initiates in the collisional regime but may transition into the collisionless regime as the fragmentation of the current sheet progresses toward kinetic scales. Hall magnetohydrodynamics (MHD) models are widely regarded as a simplified yet effective representation of the transition from collisional to collisionless reconnection. However, plasmoid instability in 2D Hall MHD simulations often leads to a single-X-line reconnection configuration, which significantly differs from fully kinetic particle-in-cell simulation results. This study shows that single-X-line reconnection is less likely to occur in 3D compared to 2D. Moreover, depending on the Lundquist number and the ratio between the system size and the kinetic scale, Hall MHD can also realize 3D self-generated turbulent reconnection. We analyze the features of the self-generated turbulent state, including the energy power spectra and the scale dependence of turbulent eddy anisotropy. 

Chalcogenide phase-change materials (PCMs) offer a promising approach to programmable photonics thanks to their nonvolatile, reversible phase transitions and high refractive index contrast. However, conventional designs are limited by global phase control over entire PCM thin films between fully amorphous and fully crystalline states, which restricts device functionality and confines design flexibility and programmability. In this work, we present a novel approach that leverages pixel-level control of PCM in inverse-designed photonic devices, enabling highly reconfigurable, multi-functional operations. We integrate low-loss Sb2Se3 onto a multi-mode interferometer and achieve precise, localized phase manipulation through direct laser writing. This technique allows for flexible programming of the photonic device by adjusting the PCM phase pattern rather than relying on global phase states, thereby enhancing device adaptability. As a proof of concept, we programmed the device as a wavelength-division multiplexer and subsequently reconfigured it into a mode-division multiplexer. Our results underscore the potential of combining inverse design with pixel-wise tuning for next-generation programmable phase-change photonic systems.