Technobius Physics

Comprehensive Overview of X-Ray Diffraction: Principles, Techniques, and Applications in Material Science

Hersh F Mahmood — 2025-08-06

This paper provides an overview of XRD, including its principles, instrumentation, data analysis, and applications. While visual characteristics can aid in identifying certain minerals, powder XRD remains the most reliable and accurate method for phase identification and structural analysis. Beyond crystallography, XRD offers valuable insights into the short- and intermediate-range structures of amorphous materials such as glasses, revealing its broader relevance in emerging technologies. It is widely used for analyzing powders, solids, thin films, and nanomaterial. XRD is often combined with techniques like SEM, TEM, PCS, EBSD, SPM, DLS, ND, and SAED to enhance material characterization. The paper covers fundamental principles such as Bragg’s Law and X-ray interaction with crystal lattices, as well as advancements in XRD instrumentation, including X-ray sources, diffractometer, and detectors, reflecting the rapid scientific progress in XRD technology.

Correlation between surface nanomorphology and charge density waves in 1T-TaS₂

Anton Shuravin — 2025-09-09

This study investigates the structural and electronic properties of 1T-TaS₂ using scanning tunneling microscopy (STM) and complementary Fourier analysis. The objective was to correlate surface morphology with the emergence of commensurate charge density wave (CDW) order and to quantify the periodicities governing its modulation. High-resolution STM imaging revealed both the atomic lattice and the superimposed CDW, with measured lattice constant of 0.343 ± 0.02 nm and CDW periodicities of 1.1 ± 0.05 nm and 2.0 ± 0.05 nm. Fourier transforms confirmed reciprocal vectors of 2.9 ± 0.1 nm⁻¹ for the lattice and 0.5–0.9 ± 0.1 nm⁻¹ for the CDW, rotated by approximately 30° with respect to the atomic lattice, consistent with a commensurate × reconstruction. Surface roughness characterization showed root-mean-square variations of 3.5 ± 0.2 nm and terrace widths of only 25–40 nm, reflecting the brittle nature of the crystal and highlighting constraints for achieving atomically stable imaging. Bias-dependent measurements demonstrated contrast inversion between filled and empty states, providing direct evidence of the electronic origin of the CDW. These results confirm the robustness of CDW ordering in 1T-TaS₂, address the research objective of linking morphology with electronic superstructures, and highlight both the opportunities and challenges of using this material as a platform for studying correlated electron phenomena in low-dimensional solids.

Quantum effects in weak gravitational fields: towards tabletop tests of quantum gravity

Elmira Sayabekova — 2025-09-14

This study explores quantum effects in weak gravitational fields with the aim of identifying feasible pathways towards tabletop tests of quantum gravity. Using numerical simulations of matter-wave interference for nanoparticles with masses between and kg, we investigate how environmental and fundamental decoherence mechanisms shape observable signatures. The results reveal a mass-dependent reduction in interference visibility, dropping from near unity at kg to below 0.2 at kg. Coherence times were found to exceed one second for particles lighter than 10^(-16) kg under cryogenic ultra-high-vacuum conditions, but decreased to sub-millisecond scales for kg particles at room temperature, confirming thermal radiation as the dominant source of decoherence. In parallel, collapse models such as CSL predict additional suppression of visibility for interrogation times of 0.1 s, particularly for masses above kg, enabling discrimination between environmental and intrinsic decoherence mechanisms. These findings underscore the necessity of maintaining ultra-high vacuum and cryogenic environments to detect gravitationally induced quantum phases, thereby providing a practical framework for near-future interferometry experiments. While the present work is limited to phenomenological models and simulated data, it establishes a roadmap for extending investigations to heavier mass regimes, incorporating realistic noise sources, and testing alternative collapse scenarios.

Numerical framework for simulating quantum spacetime fluctuations with prescribed spectra

Do-Yoon Lee — 2025-09-22

Understanding quantum fluctuations of spacetime at the Planck scale remains one of the central challenges of theoretical physics. This study introduces a stochastic framework to model such fluctuations, aiming to test whether a phenomenological approach can reproduce expected statistical signatures of quantum geometry. The metric field was represented as a one-dimensional Gaussian process with a prescribed power spectrum, and its Fourier modes were evolved through an Ornstein–Uhlenbeck process to enforce stationarity. Numerical simulations were carried out on a discretized domain with periodic boundary conditions, and statistical analyses were performed on power spectra, spatial correlations, temporal autocorrelations, and field distributions. The results showed that the empirical power spectrum reproduced the target distribution across more than two decades in wavenumber, with a clear suppression of high-frequency modes due to ultraviolet damping. The spatial correlation function indicated a coherence scale of approximately 150–200 Planck lengths, beyond which fluctuations decorrelate, making spacetime effectively smooth at larger scales. Temporal autocorrelations decayed exponentially with a relaxation time of about 200 Planck units, demonstrating that spacetime fluctuations possess finite memory. The field amplitudes followed a Gaussian distribution, supporting the assumption of central-limit behavior in the linear regime. Stationary field snapshots confirmed equilibrium behavior throughout the simulation. Overall, the study establishes a reproducible and computationally efficient framework for simulating Planck-scale metric fluctuations. The findings highlight short correlation lengths, finite coherence times, and Gaussian statistics as key features of quantum spacetime, providing a bridge between phenomenological modeling and fundamental theory.

Thickness- and gate-tunable ferromagnetism in low-dimensional Fe₃GeTe₂ nanoflakes

Zhang Wei — 2025-09-30

This study investigates thickness- and gate-dependent magnetism in low-dimensional van der Waals ferromagnet Fe₃GeTe₂ nanoflakes. The objective was to quantify how critical magnetic parameters evolve when approaching the two-dimensional limit and under electrostatic carrier modulation. High-quality single crystals were grown by self-flux, and flakes with thicknesses between 7.5 and 26 nm were isolated, encapsulated with hexagonal boron nitride, and fabricated into Hall-bar devices. Magnetotransport, polar magneto-optical Kerr effect, and SQUID magnetometry were employed to probe Curie temperature, coercive field, anisotropy, anomalous Hall conductivity, and interlayer exchange. The results reveal a systematic reduction of Curie temperature from 206 K at 26 nm to 156 K at 7.5 nm, consistent with finite-size scaling. Coercive field increased nearly threefold across the same thickness range, accompanied by high anisotropy fields of 4–6 T, indicating enhanced surface-driven perpendicular magnetic anisotropy. Anomalous Hall conductivity rose with thickness and was dominated by intrinsic Berry curvature contributions. Magneto-optical measurements confirmed weakening of interlayer exchange coupling from 0.12 to 0.06 mJ·m⁻² as thickness decreased, marking the crossover toward quasi-two-dimensional behavior. Electrostatic gating of intermediate-thickness flakes shifted the Curie temperature by approximately 5 K per 10¹³ cm⁻² carrier density and reduced coercivity by about 10%, demonstrating effective electrical control of itinerant ferromagnetism. These findings establish a coherent picture of how thickness and carrier density tune magnetic order in Fe₃GeTe₂ nanoflakes. The results address the central research problem and highlight pathways for exploiting electrically tunable two-dimensional magnets in low-power spintronic applications.