Technobius Physics

Hydrostatic compression-driven lattice crossover, electronic metallization, and fermi surface reconstruction in few-layer 1T'-MoTe2

Adolf Kim — 2026-09-28

This study investigates the structural, lattice dynamic, electronic, and Fermi surface evolution of exfoliated few-layer 1T'-molybdenum ditelluride (1T'-MoTe2) under hydrostatic pressure. Using a combination of atomic force microscopy, in-situ high-pressure micro-Raman spectroscopy, temperature-dependent four-probe electrical transport, and high-field magnetotransport within a diamond anvil cell, the material's phase behavior was systematically traced up to extreme pressures. Atomic force microscopy confirms uniform, atomically smooth flakes with an average thickness of 8.5 nm (approximately 12 layers). High-pressure Raman spectroscopy demonstrates a universal blue-shift of optical phonon modes and identifies a structural crossover near 4.8 GPa, characterized by the complete quenching of the vibrational mode and a sharp reduction in mode pressure coefficients. Electrical transport measurements reveal a pressure-induced transition from a semiconducting state with a 42.1 meV thermal activation energy to a fully metallic state at 8.2 GPa, displaying Fermi-liquid quadratic resistance scaling at low temperatures under 14.5 GPa. Furthermore, high-field magnetotransport at 12.8 GPa unveils a large, non-saturating magnetoresistance reaching 420% at 9 T alongside distinct Shubnikov–de Haas quantum oscillations. Fast Fourier Transform analysis resolves fundamental oscillation frequencies at 142 T and 285 T, corresponding to a light cyclotron effective mass of 0.12 electron masses. These findings establish hydrostatic pressure as a powerful knob for tuning electronic band structures and Fermi surface topology in transition metal dichalcogenides, providing critical insights for the development of strain-engineered quantum devices and phase-change electronics.

Structural disorder induced enhancement of dielectric energy storage performance in lead-free ceramics

Alexey Fedorov — 2026-09-28

The development of lead-free dielectric ceramics with simultaneously high recoverable energy density, high energy-storage efficiency, and excellent operational stability remains a significant challenge for advanced electrostatic capacitors. In this work, the influence of controlled structural disorder on the structural evolution, dielectric response, polarization behavior, and energy-storage performance of lead-free ceramics was systematically investigated. Ceramic samples with different levels of compositional disorder were synthesized using a conventional solid-state reaction route and characterized by X-ray diffraction, field-emission scanning electron microscopy, dielectric spectroscopy, and polarization measurements under high electric fields. The results demonstrated that increasing structural disorder refined the grain structure, enhanced lattice distortion, and promoted the transition from normal ferroelectric to relaxor behavior. The optimized composition exhibited the highest maximum polarization of approximately 52 μC cm⁻² together with a low remanent polarization of about 3 μC cm⁻², resulting in a recoverable polarization difference of nearly 49 μC cm⁻². Owing to the combined effects of improved polarization reversibility and enhanced dielectric breakdown strength approaching 480 kV cm⁻¹, a recoverable energy density of approximately 5.8 J cm⁻³ and an energy-storage efficiency close to 89% were achieved. Furthermore, the optimized ceramic maintained stable energy-storage characteristics over a wide temperature range and under different operating frequencies, indicating excellent thermal and frequency stability. These findings demonstrate that controlled structural disorder is an effective strategy for simultaneously optimizing polarization reversibility, dielectric breakdown strength, and dielectric energy-storage performance, providing a promising pathway for the design of high-performance lead-free dielectric ceramics for advanced pulse power and electrostatic energy-storage applications.

Experimental demonstration of tunable electromagnetic localization in varactor-integrated anisotropic metamaterials

Alexander Afanasyev — 2026-09-29

The dynamic manipulation of electromagnetic wave localization is essential for the development of next-generation adaptive microwave and photonic devices. This study presents a physics-informed digital twin for investigating resonance evolution and electromagnetic energy localization in voltage-tunable anisotropic metamaterials. The proposed computational framework integrates parametric geometry generation, full-wave electromagnetic simulations, equivalent-circuit modeling, constitutive-parameter retrieval, near-field analysis, and uncertainty quantification into a unified workflow. The influence of structural anisotropy and reverse-bias voltage on the resonance characteristics, effective electromagnetic parameters, and field localization was systematically evaluated over the X-band frequency range. The digital twin predicted a continuous resonance-frequency tuning of approximately 0.40 GHz under voltage control while preserving stable resonant behavior. Increasing the anisotropy coefficient enhanced the normalized peak electric-field intensity by approximately 33.5%, reduced the localization radius by 21.8%, and increased the inverse participation ratio from 0.312 to 0.417, indicating significantly stronger electromagnetic energy confinement. Retrieval of the effective constitutive parameters demonstrated increasingly pronounced dispersive behavior associated with enhanced electric and magnetic resonances. Sensitivity and robustness analyses further confirmed the numerical stability of the computational framework, with coefficients of variation below 3.3% for all principal output parameters. The results reveal that electromagnetic wave localization originates from the cooperative interaction between geometry-induced inductive enhancement and electrically controlled capacitive tuning, providing two complementary mechanisms for resonance manipulation. The proposed digital twin offers a robust computational platform for the virtual design and optimization of tunable metamaterials, reconfigurable metasurfaces, and adaptive microwave devices.

Thermal-cycling memory and non-equilibrium relaxation in defect-containing crystalline solids

James Whiteker — 2026-09-28

Thermal history can strongly influence the nonequilibrium state of defect-containing crystalline solids, yet the persistence and quantitative evolution of such memory effects remain insufficiently characterized. This study experimentally investigates thermal-cycling memory and nonequilibrium relaxation using thermoluminescence, thermally stimulated current, quenching-temperature measurements, and time-dependent electrical relaxation. Repeated thermal cycling was performed over a controlled temperature range, followed by quantitative analysis of the thermoluminescence intensity, peak position, retained state, and relaxation kinetics. The results show a progressive reduction in the thermoluminescence response with increasing cycle number, accompanied by a shift of the dominant emission maximum toward higher temperature. After ten cycles, the normalized peak and integrated thermoluminescence intensities decreased to 0.842 and 0.790, respectively. The thermal-memory response increased with maximum treatment temperature, reaching approximately −0.16, −0.27, and −0.38 at 350, 375, and 400 K, respectively. Electrical relaxation measurements revealed a decrease in the characteristic relaxation time from approximately 1750 to 760 min as the maximum treatment temperature increased. Heating-rate measurements demonstrated a systematic shift of the thermally stimulated current maximum, while Arrhenius analysis yielded an effective activation energy of approximately 0.355 ± 0.003 eV. eV. The combined results demonstrate that thermal cycling produces a reproducible nonequilibrium state whose magnitude and relaxation depend on thermal history. These findings establish a quantitative experimental framework for assessing thermal memory and defect-mediated relaxation in crystalline solids.

Experimental study of acoustic memory in mechanically compacted granular materials

Lyazzat Borankulova — 2026-09-30

This study investigates acoustic memory and post-loading acoustic relaxation in mechanically compacted granular materials. The objective was to determine whether acoustic measurements can characterize changes in the mechanical state of a granular packing and retain information about its previous loading history. Experiments were performed on granular assemblies subjected to controlled mechanical compaction at different strain levels. Acoustic signals transmitted through the packing were recorded after loading and analyzed in terms of signal amplitude, dominant frequency, spectral entropy, and relaxation behavior. Repeated loading cycles were additionally used to evaluate the development of acoustic memory during mechanical conditioning. Mechanical compaction produced a progressive increase in the stress response, accompanied by a rise in acoustic RMS amplitude from 0.797 ± 0.020 to 1.049 ± 0.055 mV. The dominant frequency increased from 19.83 ± 0.11 to 21.00 ± 0.12 kHz, while spectral entropy decreased from 2.85 ± 0.04 to 2.37 ± 0.06, indicating increasing concentration of acoustic energy around the dominant spectral components. The characteristic relaxation time increased from 36.6 ± 3.7 to 70.7 ± 6.4 s, whereas the stretching parameter decreased from 0.934 ± 0.022 to 0.742 ± 0.029, demonstrating progressively slower and more heterogeneous relaxation. The acoustic memory index increased from approximately 0.84 to 0.92 during repeated conditioning cycles. The results indicate that the measured acoustic parameters can provide a non-destructive means of tracking both the instantaneous mechanical state and loading history of granular materials. The combined analysis of amplitude, frequency, spectral entropy, and relaxation provides a practical framework for monitoring mechanical conditioning and memory in disordered granular media. A Friedman test for the repeated-cycle measurements gave χ²(4) = 18.40, p = 0.0010, with Kendall's W = 0.92.