Journals
2026 EN
Sinner Andreas · Wang XiGuang · Chotorlishvili Levan
ABSTRACT We study the thermodynamics of the recently proposed superconducting Josephson junction diode, in particular its specific heat capacity. Its low temperature behavior is determined by the interplay of two intrinsic energy scales of the microscopic Hamiltonian, associated with the superconducting gap and tunneling amplitude of conventional electrons through the junction. If the latter is large enough to overcome the former, the specific heat decays linearly with temperature, reflecting the presence of a current through the diode. In the opposite case, the specific heat decays exponentially and the diode becomes non‐conducting. In the intermediate regime, where both scales are equally large, the specific heat exhibits a non‐trivial power‐law behavior in terms of the temperature. It is demonstrated, that switching on and off of the device is possible by changing the phase of the superconducting condensate only, which is accessible via an external magnetic field. Having magnetic textures hosting magnetic defects, such as skyrmions, antiskyrmions or domain walls as sources of such magnetic field leaves behind unique defect specific footprints in the specific heat.
Journals
2026 EN
Jin Xia · Liu Dong Chang · Shi Yu
+3 more
ABSTRACT The ground‐state phase transition for the spin‐1/2 Heisenberg chain with z $z$ ‐direction dimerized anisotropy is investigated by exploiting the infinite time‐evolving block decimation algorithm. Phase boundaries are identified by examining the von Neumann entropy, entanglement spectrum, and several of fidelity indicators. The phase diagram features the existence of a tri‐critical point, which signifies the complete convergence of the transition boundaries separating the Odd‐Haldane, Even‐Haldane, and Néel phases. Specifically, the high‐precision fit of the Tomonaga–Luttinger liquid parameter provides evidence for a Tomonaga–Luttinger liquid phase line which splits the Odd‐Haldane and Even‐Haldane phases. Along this critical line, it is found that the critical exponent β $\beta$ exhibits a variation with the bond dimerization strength, which is according to a power‐law scaling. This provides a crucial theoretical framework for analyzing critical behaviors associated with topological phase transitions in quantum many‐body systems. From the odd and even string order parameters and the non‐local Néel order parameter, the Haldane phases and the Néel phase are characterized. Furthermore, the central charge and critical exponent are identified by performing a scaling analysis of finite correlation length and order parameters, indicating that the phase transition between the Haldane phases and Néel phase belongs to the classical Ising universality class, as well as a Gaussian phase transition between two types of Haldane phases.
Journals
2026 EN
Natori Willian M. H.
ABSTRACT Quantum spin liquids (QSLs) are magnetically frustrated phases characterized by spin fractionalization, emergent gauge fields, and long‐range entanglement. Quantum spin–orbital liquids (QSOLs) form a subset of QSLs with fluctuating orbital degrees of freedom, normally adding a layer of complexity to an already involved research field. This topical review provides guidelines for understanding a specific type of QSOL in which the orbital operators facilitate the analysis of quantum liquids, thereby providing adequate starting points for /exploring these phases. Such models are extensions of the spin‐1/2 Kitaev honeycomb model (KHM), in the sense that their exact solutions depend on an extensive number of conserved quantities, combined with a mapping to a problem of Majorana fermions hopping on a static gauge field. The starting points to understand such models are classical Hamiltonians characterized by bond‐dependent Ising interactions. Such classical models are exactly solvable in spin basis thanks to their extensive symmetries and can be directly connected to classical spin ice (CSI) systems that satisfy aZ 2 $Z_2$ Gauss law. QSOLs are easily stabilized in these models by applying a transverse field or introducing other exchange mechanisms that preserve the conserved local operators. The theory of such Ising QSOLs bridges the KHM to specific types of CSIs, thus providing further insight into paradigmatic forms of spin liquids. Furthermore, bond‐dependent Ising models are related to minimal Hamiltonians describing Rydberg‐atom simulations, which provide experimental grounds for investigating them.
Journals
2026 EN
Ye Weixiang
ABSTRACT Particle plasmons, the collective oscillations of conduction electrons in metal nanoparticles, are central to nanophotonics and quantum technologies. Their quantum coherence is degraded by both energy relaxation and pure dephasing. While the former is well described by classical and semiclassical models, a fundamental microscopic understanding of pure dephasing, which destroys phase coherence without energy exchange, remains elusive. This work establishes a microscopic theory by identifying stochastic resonance frequency fluctuations as the physical origin of pure dephasing in particle plasmons. Starting from a many‐body electron Hamiltonian, we map the plasmon onto a quantum harmonic oscillator via collective coordinates and the random phase approximation. We demonstrate that environmental perturbations commuting with the plasmon number operator induce random frequency shifts, leading to phase diffusion. We then microscopically derive contributions from three dominant mechanisms: electron‐phonon scattering, defect scattering, and surface roughness scattering. These contributions are unified into a general scaling law that predicts the pure dephasing rate as a function of nanoparticle size and geometry, revealing a crossover between dominant mechanisms. This law provides a microscopic foundation for empirical damping formulas and clarifies the fundamental distinction between energy relaxation and pure dephasing, thereby completing the quantum mechanical picture of plasmon decoherence.
Journals
2026 EN
Chen Dingkun · Zhuo Jianliang · Song Zhengyong
ABSTRACT Metasurfaces offer unprecedented capabilities for manipulating electromagnetic wave, but simultaneous and independent generation of diverse functionalities like holography, orbital angular momentum (OAM), and grayscale imaging (GI) within a single platform remains a challenge. Here, we demonstrate a terahertz bilayer metasurface. It leverages insulator‐metal phase transition of vanadium dioxide (VO 2 ) for dynamic control. The metasurface integrates spin‐decoupled theory and Malus’ law to achieve multifunctional wavefront engineering. As VO 2 is metallic, a vortex beam (VB) with topological charge (TC) of l = 1 is gained under left‐handed circular polarization (LCP) incidence, while a distinct hologram image (HI) A is obtained under right‐handed circular polarization (RCP) incidence. Concurrently, GI 6 is observed in near field under x‐polarized incidence. As VO 2 is insulating, it dynamically reconfigures metasurface's response. HI H is generated in LCP channel, and VB with TC = −2 is formed in RCP channel. Meanwhile, GI 3 with x polarization appears in near field. Through rigorous numerical simulations, we validate independent control and high‐quality performance of each channel. This work demonstrates a versatile platform for achieving complex and switchable optical operations.
Journals
2026 EN
Tun Htet Myet · Keawmaungkom Sutthinee · Srimongkol Siwaporn
+8 more
ABSTRACT Conductive natural rubber composites (CNRs) filled with carbon black (CB) are widely explored for flexible sensing applications due to their tunable electrical properties. This study introduces a simulation framework integrating Monte Carlo methods with two representative volume element (RVE) models—uniform (Uni‐RVE) and overlap face‐centered cubic (OFCC‐RVE)—to investigate the electrical conductivity and percolation behavior in CB‐filled CNRs. An onion‐like progressive tunneling effect is introduced to represent the distance‐dependent conductivity more realistically. The OFCC‐RVE model, incorporating particle agglomeration and variable tunneling distances, demonstrates strong agreement with experimental data. A power‐law decay function is applied to capture conductance attenuation at different interparticle distances. The model achieves a mean absolute percentage error of 5.2% when compared with experimental measurements, highlighting its predictive accuracy and efficiency. This approach provides a computationally efficient and physically grounded framework for evaluating and optimizing the electrical performance of conductive rubber composites.
Journals
2026 EN
Munizza Gabriela V. · Eisenberg Patricia
ABSTRACT Biodegradable polycaprolactone (PCL) films were developed with 13% w/w ethanol extract from industrial peanut skin residues (PSE), a rich source of natural antioxidants and antimicrobials. Films retain actives during processing. Antioxidant activity was evaluated via total phenolics, flavonoids, condensed tannins, and radical scavenging assays (DPPH, ABTS). PSE incorporation enhances oxidative thermal stability, increasing oxidation onset temperature (OOT) by 61°C—eliminating the early oxidative stage of neat PCL—and extending oxidation induction time (OIT), without compromising suitability for food packaging. Oxidative stability is maintained after accelerated storage (90 days at 40°C) and repeated migration tests simulating contact with refrigerated fatty foods. Migration assays confirm effective release of actives under repeated use. Mass transfer parameters were obtained by fitting experimental data to Fick's second law and the Arrhenius model, yielding intrinsic diffusion coefficients in 95% ethanol from 5°C to 40°C (4.17 × 10 −15 –7.1 × 10 −14 m 2 ·s −1 ), eliminating swelling at 40°C. Coefficients fall within typical polymer–antioxidant ranges, reflecting strong retention and controlled release due to the PCL matrix and complex PSE mixture. Overall, the films demonstrate long‐term chemical and functional stability, enhanced thermo‐oxidative resistance, and controlled antioxidant release, supporting their application in refrigerated, lipid‐rich foods within a circular economy framework.
Journals
2026 EN
Ignasius Haidy · Najidha S. · Sankar S.
ABSTRACT This study investigates dielectric relaxation, electrical conductivity, and charge transport mechanisms in pristine polypyrrole (PPy) and carbon black (CB)–doped polypyrrole (PPy/CB) composites synthesized via in situ polymerization. Structural and morphological characterization using XRD, FTIR, Raman spectroscopy, and SEM confirms the successful incorporation and homogeneous dispersion of CB within the PPy matrix. Broadband dielectric spectroscopy (BDS) measurements carried out over the frequency range of 10 −1 –10 7 Hz reveal a systematic evolution of dielectric and transport behavior with increasing CB content. The dielectric constant ( ε ′) decreases with CB loading, indicating a transition from polarization dominated dielectric behavior to conduction dominated electrical response. DC conductivity increases markedly from nearly insulating pristine PPy to 0.032 S cm −1 for the PPy/CB composite containing 10 wt% CB. The frequency dependent AC conductivity follows Jonscher's universal power law with exponent values between 0.5 and 0.7, suggesting charge transport via localized hopping in a disordered system. Cole–Cole model analysis confirms broad, non‐Debye relaxation processes across all compositions. The combined σ ′– σ ″ dispersion, impedance ( Z ′– Z ″) behavior, and asymmetric relaxation parameters provide clear evidence that charge transport is governed by frequency activated hopping and strong interfacial Maxwell–Wagner–Sillars polarization at PPy–CB interfaces. These enhanced dielectric and electrical properties highlight the potential of PPy/CB nanocomposites for electronic, sensing, and energy storage applications.
Journals
2026 EN
Ahmed Waqas · Li Hui · Liu Jun
+3 more
ABSTRACT Polymethyl methacrylate (PMMA) is widely used in medical, marine, and engineering structures due to its excellent physical and mechanical properties. However, its susceptibility to water absorption threatens long‐term performance and dimensional stability, necessitating a thorough understanding of its water absorption behavior. This study investigates the effects of specimen thickness on the time‐dependent diffusivity and water absorption behavior of PMMA. Experiments were conducted on samples with five different thicknesses (3.2, 6.4, 9.6, 12.8 and 16.0 mm) to analyze absorption kinetics and determine diffusion coefficients. Results confirmed Fickian diffusion behavior and revealed that thinner specimens reached saturation faster and absorbed a higher final moisture content (1.13% vs. 0.74% for the thickest specimen), demonstrating an inverse relationship between thickness and total water uptake. A critical finding was the non‐steady nature of the diffusion coefficient, which was found to be dependent on both thickness and exposure time, exhibiting an initial high value that decayed as saturation approached. A novel three‐dimensional model derived from Fick's second law successfully captured this time‐dependent diffusion as well as accurately predicted water uptake. Accurate experimental validation confirms the model's utility as a predictive tool for assessing PMMA's long‐term sorption kinetics in water‐exposed applications.
Journals
2026 EN
Triki Abdussalam Giuma A.
ABSTRACT The South China Sea crisis remains a major geopolitical flashpoint involving overlapping territorial claims, contested legal interpretations, and increasing external interventions. This article analyzes the historical development of state claims, the legal implications of the 2016 Permanent Court of Arbitration ruling, and the evolving roles of major powers, particularly the United States and India. Incorporating recent developments, including the Philippinesʼ renewed alliance with the United States under President Marcos Jr., expanded U.S. military presence, and Indiaʼs strategic engagement through energy cooperation and the Quad, the study highlights the complex interplay of law, diplomacy, and power politics. While UNCLOS provides a normative framework, enforcement challenges persist, and strategic competition continues to intensify. This study concludes that proactive diplomacy, regional cooperation, and adherence to international norms are essential for mitigating tensions and maintaining stability in the Indo‐Pacific region.