Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>In this article, we present an efficient deep learning method called coupled deep neural networks (CDNNs) for coupling of the Stokes and Darcy-Forchheimer problems. Our method compiles the interface conditions of the coupled problems into the networks properly and can be served as an efficient alternative to the complex coupled problems. To impose energy conservation constraints, the CDNNs utilize simple fully connected layers and a custom loss function to perform the model training process as well as the physical property of the exact solution. The approach can be beneficial for the following reasons: Firstly, we sampled randomly and only input spatial coordinates without being restricted by the nature of samples. Secondly, our method is meshfree which makes it more efficient than the traditional methods. Finally, the method is parallel and can solve multiple variables independently at the same time. We present theoretical results to guarantee the convergence of the loss function and the convergence of the neural networks to the exact solution. Some numerical experiments are performed and discussed to demonstrate the performance of the proposed method.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We investigate the Andreev reflection across a uniaxial strained graphene-based superconducting junction. Compared with pristine graphene-based superconducting junction, three opposite properties are found. Firstly, in the regime of the intraband conversion of electron-hole, the Andreev retro-reflection happens. Secondly, in the regime of the interband conversion of electron-hole, the specular Andreev reflection happens. Thirdly, the perfect Andreev reflection, the electron-hole conversion with unit efficiency, happens at a nonzero incident angle of electron. These three exotic properties arise from the strain-induced anisotropic band structure of graphene, which breaks up the original relation between the direction of velocity of particle and the direction of the corresponding wavevector. Our finding gives an insight into the understanding of Andreev reflection and provides an alternative method to modulate Andreev reflection.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The single crystal of cubic perovskite BaFeO<jats:sub>3</jats:sub> shows multiple magnetic transitions and external stimulus sensitive magnetism. In this paper, a 5%-Co doped BaFeO<jats:sub>3</jats:sub> (i.e. BaFe<jats:sub>0.95</jats:sub>Co<jats:sub>0.05</jats:sub>O<jats:sub>3</jats:sub>) single crystal was grown by combining floating zone methods with high-pressure techniques. Such a slight Co doping has little effect on crystal structure, but significantly changes the magnetism from the parent antiferromagnetic ground state to a ferromagnetic one with the Curie temperature <jats:italic>T</jats:italic> <jats:sub>C</jats:sub> ≈ 120 K. Compared with the parent BaFeO<jats:sub>3</jats:sub> at the induced ferromagnetic state, the saturated magnetic moment of the doped BaFe<jats:sub>0.95</jats:sub>Co<jats:sub>0.05</jats:sub>O<jats:sub>3</jats:sub> increases by about 10% and reaches 3.64 <jats:italic>μ</jats:italic> <jats:sub>B</jats:sub>/f.u. Resistivity and specific heat measurements show that the ferromagnetic ordering favors metallic-like electrical transport behavior for BaFe<jats:sub>0.95</jats:sub>Co<jats:sub>0.05</jats:sub>O<jats:sub>3</jats:sub>. The present work indicates that Co-doping is an effective method to tune the magnetic and electric properties for the cubic perovskite phase of BaFeO<jats:sub>3</jats:sub>.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Memristor has been widely studied in the field of neuromorphic computing and is considered to be a strong candidate to break the von Neumann bottleneck. However, the non-ideal characteristics of memristor seriously limit its practical application. There are two sides to everything, and memristors are no exception. The non-ideal characteristics of memristors may become ideal in some applications. Genetic Algorithm (GA) is a method to search for the optimal solution by simulating the process of biological evolution. It is widely used in the fields of machine learning, combinatorial optimization, and signal processing. In this paper, we simulate the biological evolutionary behavior in GA by using the non-ideal characteristics of memristors, based on which we design peripheral circuits and path planning algorithms based on memristor networks. The experimental results show that the non-ideal characteristics of memristor can well simulate the biological evolution behavior in GA.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We develop a minimal phenomenological model to describe the auxetic response recently observed in liquid crystal elastomers, and further determine by theoretical calculation the critical condition required for the auxetic response to occur.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>MOX (M = Fe, Cr, V; O = oxygen, X = F, Cl, Br, I), an emerging type of two-dimensional (2D) van der Waals materials, have been both theoretically and experimentally demonstrated to possess unique electronic and magnetic properties. However, the intrinsic in-plane anisotropic properties of 2D VOCl still lacks in-depth research, especially optical anisotropy. Herein, a systematic Raman spectroscopic study is performed on VOCl single-crystal with different incident laser polarization at various temperatures. The polarized-dependent Raman scattering spectra reveal that the <jats:italic>A</jats:italic> <jats:sub> <jats:italic>g</jats:italic> </jats:sub> mode of VOCl show a 2-lobed shape in parallel polarization configuration while a 4-lobed shape in vertical configuration. In addition, the temperature-dependent and thickness-dependent Raman scattering spectra confirm a relatively weak van der Waals interaction between each layers among VOCl single crystal. These findings might provide better understanding on the in-plane anisotropic phenomenon in VOCl layers, thus will accelate further application of 2D single crystals for nanoscale angle-dependent optoelectronics.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Thermo- and diffusiophoresis respectively refer to the directed drift of suspended particles in solutions with external thermal and chemical gradients, which have been widely used in the manipulation of mesoscopic particles. We here study a phoretic-like motion of a passive colloidal particle immersed in inhomogeneous active baths, where the thermal and chemical gradients are replaced separately by activity and concentration gradients of the active particles. By performing simulations, we show that the passive colloidal particle experiences phoretic-like forces that originate from its interactions with the inhomogeneous active fluid, and thus drifts along the gradient field, leading to an accumulation. The results are similar to the traditional phoretic effects occurring in passive colloidal suspensions, implying that the concepts of thermophoresis and diffusiophoresis could be generalized into active baths.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The photonic spin Hall effect has attracted considerable research interest due to its potential applications in spin-controlled nanophotonic devices. However, realization of asymmetrical photonic spin Hall effect is still a challenge with a single optical element due to the conjugation of Pancharatnam-Berry phase, which reduces the flexibility in various applications. Here, we demonstrate an asymmetrical spin-dependent beam splitter based on a single-layer dielectric metasurface exhibiting strong and controllable optical response. The metasurface consists of an array of dielectric nanofins, where both varying rotation angles and feature sizes of the unit cells are utilized to create high-efficiency dielectric metasurfaces, which enables to break the conjugated characteristic of phase gradient. Thanks to the superiority of the phase modulation ability, when the fabricated metasurface is under normal incidence with 1550 nm in wavelength, the LCP light exhibits an anomalous refraction angle of 28.9°, while the RCP light transmitted directly. The method we propose can be used for the flexible manipulation of spin photons and has potentials in high efficiency metasurfaces with versatile functionalities, especially with metasurfaces in a compact space.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Onsager–Casimir reciprocal relations are a fundamental symmetry of nonequilibrium statistical systems. Here we study an unusual chirality-dependent Hall effect in a tilted Weyl semimetal Co<jats:sub>3</jats:sub>Sn<jats:sub>2</jats:sub>S<jats:sub>2</jats:sub> with broken time reversal symmetry. It is confirmed that the reciprocal relations are satisfied. Since two Berry curvature effects, an anomalous velocity and a chiral chemical potential, contribute to the observed Hall effect, the reciprocal relations suggest their intriguing connection.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>As the global energy crisis and environmental pollution problems become more and more serious, it is important to develop new ways to improve the existing situation. Among these new technologies, the photocatalysis technology has caused widespread concern because of their huge application prospects in harnessing pollution free solar energy to degrade organic pollutants. In the other hand, from a fundamental scientific and technical standpoint, efficiently improved optical frequency is a demanding and intriguing topic, which provides a great framework for studying the optical processes impacted by the local photonic environment. This sort of study is especially pertinent since plasmonics places a greater focus on nonlinearity. Thus, the technology of near infrared (NIR) catalysis has received a lot of interest. In this review, we aim at offering an integrated framework about NIR photocatalysis. We will give a brief introduction of photocatalysis based on the upconversion (UC) materials, including the efficiency of UC materials, and the combination and energy transfer process between semiconductor and UC particles, as well as photoelectric response, photo controlled-delivery and photodynamic therapy based on the NIR-responsive materials.</jats:p>