Advanced Physics Research最新文献

Atomic Force Lithography

The study 2400108 by Dmitry Yakovlev and co-workers introduces a novel approach to using atomic force microscopy (AFM) pulse force nanolithography to fabricate Bi₂Se₃ nanoribbons with high precision. This allows control over their dimensions and prevents contamination from standard electron beam lithography or reactive ion etching. The illustration shows a pie of complex multilayer heterostructures cut into small pieces by using atomic force lithography with an accuracy of a few nanometers. The results also reveal insights into electronic structure, conductance, and phase coherence in TIs, with thermal excitation and bias current affecting coherence length. This new AFM technique offers a scalable and precise approach.

Epithelia are polarized layers of cells that line the outer and inner surfaces of organs. At the basal side, the epithelial cell layer is supported by a basement membrane, which is a thin polymeric layer of self-assembled extracellular matrix (ECM) that tightly adheres to the basal cell surface. Proper shaping of epithelial layers is an important prerequisite for the development of healthy organs during the morphogenesis of an organism. Experimental evidence suggests that local degradation of the basement membrane is one of the mechanisms that can drive epithelial folding. However, how folding emerges in the absence of tissue growth remains elusive. Here, we present a coarse-grained plate theory model of the basement membrane that assumes force balance between i) cell-transduced active forces and ii) deformation-induced elastic forces. We verify key assumptions of this model through experiments in the Drosophila wing disc epithelium and demonstrate that the model can explain the emergence of outward epithelial folds upon local plate degradation. The model accounts for local degradation of the basement membrane as a mechanism for the generation of epithelial folds in the absence of epithelial growth.

Piezomagnetic switching

In article number 2400054, Hung-Cheng Wu, Taku J. Sato, and co-workers report the first observation of a finite enhancement of the weak ferromagnetic component in a Cu-based compound under uniaxial stress, providing evidence of the piezomagnetic effect and confirming the magnetic space group determination resolved by neutron diffraction. An intriguing sign change in the piezomagnetic coefficient holds the potential for realizing new functionality in switchable magnetic domains through temperature and pressure manipulation.

Measuring protein dynamics by luminescent nanothermometry

Luminescent nanothermometry emerges as a powerful tool for studying protein dynamics. In their article 2400085, F. E. Maturi, L. D. Carlos and co-workers describe how they employed the technique to measure the temperature dependence of green fluorescent protein Brownian velocity across physiological temperatures and distinct concentrations.

Susceptibility Parameters for Perpendicularly Moving Metasurfaces

This front cover illustrates customizable electromagnetic responses from moving metasurfaces. In article number 2400073, Hongsheng Chen, Zuojia Wang and co-workers explain how the susceptibility parameters transform when a metasurface moves perpendicularly towards the sources. The duality-matching condition for moving-invariant behaviors is derived. The absorption and chirality performance can be well preserved when the designed metasurfaces move quickly.

Topological insulator nanostructures became an essential platform for studying novel fundamental effects emerging at the nanoscale. However, conventional nanopatterning techniques, based on electron beam lithography and reactive ion etching of films, have inherent limitations of edge precision, resolution, and modification of surface properties, all of which are critical factors for topological insulator materials. In this study, an alternative approach for the fabrication of ultrathin Bi₂Se₃ nanoribbons is introduced by utilizing a diamond tip of an atomic force microscope (AFM) to cut atomically thin exfoliated films. This study includes an investigation of the magnetotransport properties of ultrathin Bi₂Se₃ topological insulator nanoribbons with controlled cross-sections at ultra-low 14 mK) temperatures. Current-dependent magnetoresistance oscillations are observed with the weak antilocalization effect, confirming the coherent propagation of 2D electrons around the nanoribbon surface's perimeter and the robustness of topologically protected surface states. In contrast to conventional lithography methods, this approach does not require a highly controlled clean room environment and can be executed under ambient conditions. Importantly, this method facilitates the precise patterning and can be applied to a wide range of 2D materials.

In this study, the performance of memristive devices made of oxygen-deficient HfO₂ films is investigated when exposed to various electrical pulse stimulations. The devices exhibited signs of fatigue with the number increasing of a fixed frequency pulse, mirroring the synaptic adaptation to repeat stimuli. Interestingly, the synaptic behavior can be highly simulated by logic function, and the pulse frequency and magnitude play different roles in changing the synaptic curves. Only pulses with certain quantized frequencies can reshape the synaptic current response curve. In addition, a similarity is observed between the frequency stability of these devices and the biological lifespan in response to external stimuli. These observations strengthen the case for the potential of memristors in emulating cognitive functions.