Advanced Physics Research最新文献

Superconductor-Based Thermal Diode

In Research Article e00080, Yoshikazu Mizuguchi and co-workers report the experimental observation of thermal rectification in a bulk-superconductor-based thermal diode. The cover illustrates the Pb-Al thermal diode where the cooler part is superconducting Pb, and the hotter part is normal-conducting Al. Because of low thermal conductivity of a superconductor, the resulting effective thermal conductivity is lower than the opposite heat flow where the cooler part is normal-conducting Al, and the hotter part is normal-conducting Pb.

The emergence of intrinsic 2D magnetic materials has opened new avenues for spintronic applications. Among them, Cr_1+δTe₂ has attracted significant interest due to its near-room-temperature ferromagnetism and widely-tunable chemical stoichiometry. In this work, we demonstrate a comprehensive study on the controlled modification of magnetic and electronic transport properties in 2D Cr_1+δTe₂ through focused Ga⁺ ion irradiation. Specifically, we achieved a progressive reduction and eventual full suppression of the anomalous Hall effect (AHE) sign-reversal temperature via modulating the irradiation dose, while the Curie temperature remains notably stable. Cross-sectional and elemental mapping analyses revealed irradiation-induced structural and compositional changes, highlighting the potentially distinct role of structural amorphization and stoichiometric variation in mediating the AHE behavior and magnetic ordering. The discovery of residual magnetism and tunable AHE in the amorphized structures establishes focused ion beam irradiation as a viable method for designing crystalline/amorphous architectures, offering great promise for the design of novel functionalities.

This study investigates the plasmonic properties of TiN thin films deposited by pulsed mid-frequency reactive magnetron sputtering combined with RF inductively coupled plasma in a DC magnetic field and electron cyclotron wave resonance (ECWR). The substrate was grounded while the plasma potential was tuned by applying a positive DC bias from 0 to 120 V to the ECWR coil relative to ground. Raising the DC bias increased the plasma potential and thus accelerated ions to energies corresponding to that potential, producing energetic ion bombardment of the grounded substrate. The principal benefit of adding ECWR plasma and a DC bias is an increased degree of ionization in the reactive plasma. Consequently, the resulting denser plasma and enhanced N₂ dissociation improve the internal structure of the deposited films even at low substrate temperatures.

The current market launch of HfO₂ -based ferroelectric devices relies on the control of the inherent oxygen vacancies (OVs) and their impact on the ferroelectric performance. Due to the necessary stabilization of the ferroelectric phase by doping, several dopants are investigated for their applicability to control the vacancy concentration. Hf $$ signatures in X-ray photoemission spectra are often used as an indication of OVs for both qualitative and quantitative analysis. The analysis of Y doped HfO₂ (Y:HfO₂) as investigated by hard x-ray photoelectron spectroscopy (HAXPES) reveals the inapplicability of the Hf $$ signature for a quantitative determination of OVs in the case of heterovalent doping and is restricted to pure HfO₂ or isoelectronic substitution of Hf by, for example, Zr.

Resistive switching memory has emerged as a promising candidate for next-generation data storage and is regarded as a key enabler for the advancement of artificial intelligence technologies. However, conventional resistive memory architectures face critical challenges, including sneak-path current interference, poor scalability, and limited integration density, which hinder their practical deployment in high-density neuromorphic systems. In this study, a self-rectifying 3D 2 × 2 crossbar array based on a diode–memristor–diode (DMD) architecture using a Pt/SrMnO₃/Pt configuration is demonstrated for the first time, exhibiting excellent electrical performance and outstanding operational stability. The device effectively suppresses sneak-path currents, thereby enabling the integration of high-density memory arrays. The reset process is quantitatively analyzed through machine learning applied to electrical transport characteristics, while the high-resistance state is accurately described using the Poisson–Boltzmann formalism. These results highlight the significant potential of the stacked Pt/SrMnO₃/Pt structure for next-generation non-volatile memory and provide a solid foundation for its application in neuromorphic computing and artificial neural networks.

This study explores the integration of atomic layer deposited (ALD) HfO₂ dielectric films with solution-processed In₂O₃ semiconductor channel, thin-film transistors (TFTs) for a silicon chip-free temperature sensor label. The inclusion of the HfO₂ high-κ dielectric permits reduced voltage operation of the sensor label. HfO₂ films are deposited by atomic layer deposition (ALD) at three different hot source temperatures (80°C, 90°C, 100°C), with XPS revealing improved stoichiometry and O/Hf ratios of 1.75, 1.92, and 1.95, respectively, as temperature increases. MOSCAP measurements show improved oxide/semiconductor interface with higher deposition temperatures. The extracted dielectric constants (ε_r ≈ 18.5–18.8) correspond to an equivalent oxide thickness (EOT) of about 3.1 nm, consistent with optimized high-κ film formation. To enhance drain current, a reduced 7.5 nm HfO₂ film thickness is used, achieving higher current but reducing yield by 30% due to increased leakage probability in ultrathin films. A voltage divider circuit is developed to integrate an electrochemical thermal sensor, TFT, and an irreversible visual indicator (IVI), allowing for temperature monitoring with a resistivity change of three orders of magnitude at 8°C. The circuit is powered by a 60 mF supercapacitor array providing approximately 0.21 J of available energy, resulting in IVI activation within 40 min at measured activation currents of 20 µA. The system demonstrates potential for low-voltage, energy-efficient, silicon-free sensor labels in applications such as food safety and healthcare monitoring.

Liquid metals possess excellent electrical conductivity, fluidity, and high density, exhibiting unique electroresponsive characteristics under applied electric fields. This article systematically investigates the instantaneous response, frequency synchronization, and resonance phenomena of gallium-based liquid metal droplets under square-wave alternating electric fields. We comprehensively clarify the effects of droplet volume, alloy composition, electric field intensity, and mechanical confinement on electrically induced resonance behavior. In free spaces, we reveal a critical transition in governing laws characterized by the modified Bond number (Bo_m) as the dimensionless parameter. We observe coordinated linear responses of transverse and longitudinal amplitudes to applied electric field amplitude for liquid metal droplets with Bo_m < 1, while droplets with Bo_m > 1 exhibit nonlinear responses featuring asymmetric deformation and multi-modal transitions. Within confined channels, droplets display multi-mode standing wave patterns, with the number of surface wave crests correlating with droplet volume. Multi-droplet systems display collective dynamics modulated by array size and the spatial positioning of droplets within the collective. These findings establish theoretical foundations for controlling and amplifying the electrically induced behavior of positionally stable liquid metal droplets, and open new pathways for developing liquid metal resonance-based multi-excitation point mixers, flexible actuators, and reconfigurable electronic systems.

Transition metal penta-tellurides, ZrTe₅ and HfTe₅ have recently drawn a lot of attention due to their fascinating physical properties and for being prominent materials showing topological phase transitions. In this work, we present first in-depth investigation of elasto-mechanical, thermophysical, and optical properties of these compounds. In particular, we analyzed the directional dependence of the elastic properties, explored the optical response for different photon polarization directions and examined previously unreported potential industrial applications of these materials. We also studied their electronic and topological properties. We used Density Functional Theory (DFT) based calculations to study all of these properties. This study suggests that the materials are mechanically stable, possess high mechanical and bondinganisotropy, are soft and brittle in nature. Investigation of thermophysical properties indicates weak bonding strength in these compounds and suggests their possible application in acoustic and thermoelectric devices. Examination of their optical characteristics reveals that they have high refractive indices at low energy. They are very good ultraviolate absorbers and potential candidates for solar coating devices. Our study also reveals that these materials show characteristics of weak ℤ₂ topological insulators. Spin-orbit interaction is responsible for enhancing energy gaps and promoting insulating characteristics in these compounds.