Abstract WTe$_2$ recently attracted considerable attention as a layered material exhibiting ferroelectricity, giant magnetoresistance, and pressure-induced superconductivity. In this study, we performed Raman spectroscopy on bulk WTe$_2$, including the low-frequency region. An unfamiliar Raman peak (P0) was found at approximately 9 cm$^{-1}$ in addition to the seven already known peaks (P1--P7). Furthermore, the angular and polarization dependence of the spectra revealed the peak P0 had A$_1$ symmetry. The symmetry is consistent with the experimental results and first-principles calculations by other groups. Our work paves the way for studying the symmetry of the low-frequency phonons in atomic-layer ferrolectric films using Raman spectroscopy.

Abstract We report current-induced magnetization switching (j sw) with a nanosecond-duration pulse current (t p) in a perpendicularly magnetized nanomagnet under the Dzyaloshinskii-Moriya interaction (DMI) and investigate the effect of the Gilbert damping constant (α), t p, and DMI value (D) on j sw via micromagnetic simulations. When α is sufficiently small at t p = 1 ns, j sw for D = 1.0 erg/cm2 decreases by 42% compared to that for D = 0 erg/cm2. Further, j sw can be reduced under the DMI when α is small and t p is short, which is attributed to the twisted magnetization and increased initial magnetization angle.

Abstract We present the thermal conductivity (κ) of perovskite PbZr1−xTixO3 (PZT) for 0 ≤ x ≤ 1 and 300 K ≤ T ≤ 873 K, the composition and temperature ranges covering the classic phase diagram of this important piezoelectric system. The glasslike dκ/dT > 0 behavior is observed for the ferroelectric rhombohedral phases and much of the paraelectric cubic phase, implying the presence of strong phonon damping in these regions of PZT. For all the temperatures studied in this work, the κ becomes lowest at x = 0.5.

During surface-enhanced fluorescence processes, the spatial spacing layer on the surface of noble metals plays an important role in regulating the fluorescence intensity. We propose a method for regulating fluorescence intensity using the AgNPs@TA-FeIII composite nanostructured materials as the substrate and using characteristic fluorescence of graphene quantum dots as the detection signal. Tannins-FeIII (TA-FeIII) nanofilms were prepared with a one-step assembly method, which is simple, fast, green, and safe. This work is expected to help the application of polyphenol metal nanofilm technology in the field of surface enhanced fluorescence (SEF).

This study investigated the crystallographic plane dependence of the reaction of AlN and AlGaN using heated-pressurized water under saturated vapor pressure. The results show that the reaction strongly depends on the crystallographic orientation plane, with no reaction in the +c-plane, the formation of an AlOOH-altered layer in the −c-plane, and etching in the a- and m-planes. These results suggest that the exfoliation mechanism of AlGaN grown on periodically formed AlN nanopillars on sapphire substrates using heated-pressurized water involves etching of a- and m-plane crystals, demonstrating that the proposed method is highly reproducible and versatile for large-diameter wafer exfoliation.

We report on a single-scan polarization-resolved saturated absorption spectra (SAS) method utilizing a hybridly polarized beam as the probe. Owning to the spatial-variant polarization of a hybridly polarized probe, the polarization-resolved information can be retrieved from the single signal image. Then, the polarization dependence of SAS from two transitions are investigated. Strong polarization dependence is observed from the “closed two-level transition” as |5S 1/2, F = 3> → |5P 3/2, F′ = 4> of 85Rb. By contrast, no polarization dependence is observed from “open two-level transition” as |5S 1/2, F = 3> → |5P 3/2, F′ = 3>. The method would be meaningful for the samples with poor stability or the ultrafast processes.

In the realm of ultrashort pulse laser processing, surpassing the air ionization threshold, variations in focusing characteristics due to nonlinear optical phenomena pose challenges. Particularly, suitable irradiation conditions and position control methods for high pulse energy processing around 1 mJ remain unestablished. This study explores laser divergence phenomena in several mJ pulse energy range, examining both experimental and computational data. Quantitative demonstrations of laser focusing alterations, including divergence position and fluence, were achieved. Additionally, the dry laser peening effect was enhanced by energy-specific irradiation control. Numerical simulation-based visualization facilitates precise control, advancing the processing techniques.

Automation is an engineering method of transforming process speed, reproducibility, and scalability from the corresponding manual process. This paper proposes a simple mechanical setup for automating the exfoliation process of two-dimensional materials constructed with simple commercial parts. Given the large shear force on the adhesive tapes, the tapes can be fixed on a mechanical bar, and the other side of the tape moves with exfoliation from the substrates. The exfoliation rate can be modulated from 2 cm min−1 to 0.014 cm min−1 in the setup. The developed mechanics are simple with various customizable parameters and make the exfoliation process scalable.