Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>Recently, the discovery of vanadium-based kagome metal AV<jats:sub>3</jats:sub>Sb<jats:sub>5</jats:sub> (A = K, Rb, Cs) has attracted great interest in the field of superconductivity due to the coexistence of superconductivity, non-trivial surface state and multiple density waves. In this topic review, we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV<jats:sub>3</jats:sub>Sb<jats:sub>5</jats:sub>. We start with the unconventional charge density waves, which are thought to correlate to the timereversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV<jats:sub>3</jats:sub>Sb<jats:sub>5</jats:sub>. Then we discuss the superconductivity and the topological band structure. Next, we review the competition between the superconductivity and charge density waves at different condition of pressure, chemical doping, thickness, and strains. Finally, the experimental evidences of pseudogap pair density wave are discussed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We study the ferroelectricity in a one-dimensional system composed of a double helix SnIP with absorbing water molecules. Our <jats:italic>ab initio</jats:italic> calculations reveal two factors that are critical to the electrical polarization. The first one is the orientation of polarized water molecules staying in the R2 region of SnIP. The second one is the displacement of I atom which roots from subtle interaction with absorbed water molecules. A reasonable scenario of polarization flipping is proposed in this study. In the scenario, the water molecule is rolling-up with keeping the magnitude of its electrical dipole and changing its direction, meanwhile, the displacement of I atoms is also reversed. Highly tunable polarization can be achieved by applying strain, with 26.5% of polarization enhancement by applying tensile strain, with only 4% degradation is observed with 4% compressive strain. Finally, the direct band gap is also found to be correlated with strain.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We theoretically investigate the reflected spatial Imbert-Fedorov (IF) shift of transverse-electric (TE)-polarized beam illuminating on a bulk Weyl semimetal (WSM). The spatial IF shift is enhanced significantly at two different frequencies close to the epsilon-near-zero (ENZ) frequency, where large values of reflection coefficients |<jats:italic>r</jats:italic> <jats:sub> <jats:italic>pp</jats:italic> </jats:sub>|/|<jats:italic>r</jats:italic> <jats:sub> <jats:italic>ss</jats:italic> </jats:sub>| are obtained due to the ENZ response induced different rapid increasing trends of |<jats:italic>r</jats:italic> <jats:sub> <jats:italic>pp</jats:italic> </jats:sub>| and |<jats:italic>r</jats:italic> <jats:sub> <jats:italic>ss</jats:italic> </jats:sub>|. Particularly, the tunable ENZ effect with tilt degree of Weyl cones and Fermi energy enables the enhanced spatial IF shift at different frequencies. The enhanced spatial IF shift also shows the adjustability of WSM thickness, incident angle and Weyl node separation. Our findings provide easy and available methods to enlarge and adjust the reflected IF shift of TE-polarized light with a WSM.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The acoustic-phonon emission from monolayer molybdenum disulfide (ML-MoS<jats:sub>2</jats:sub>) driven by a direct-current electric field is studied theoretically by using the Boltzmann equation method. It is found that Cerenkov emission of terahertz acoustic-phonons can be generated when a very weak electric field is applied to ML-MoS<jats:sub>2</jats:sub>. The physical mechanisms of acoustic-phonon emission are analyzed from the perspective of condensed matter physics. The acoustic-phonon emission from ML-MoS<jats:sub>2</jats:sub> is also compared with those from graphene and GaAs. The results reveal that the frequencies of acoustic-phonons generated from ML-MoS<jats:sub>2</jats:sub> are between the frequencies of those generated from GaAs and graphene. The results of this work suggest that ML-MoS<jats:sub>2</jats:sub> can make up for graphene and GaAs in respect of acoustic-phonon emission and be used in tunable hypersonic devices such as terahertz sound sources.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The proximity effect to reduce the transition temperature of a superconducting film is frequently used in transition-edge sensors. Here, we developed these transition-edge sensors using Mo/Au/Au tri-layer films to detect soft X-rays. They were equipped with an overhanging photon absorber. We reduced the fabrication complexity by integrating the sensor patterning with the tri-layer film formation. We determined the electro-thermal parameters of the sensors through a series of resistance vs. temperature and current vs. voltage measurements. We also demonstrated their energy-resolving capability by using a <jats:sup>55</jats:sup>Fe radioactive X-ray source. The best energy resolution was approximately 6.66 eV at 5.9 keV, with a theoretical count rate of 500 Hz.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The suppression and compensation effect of oxygen on heavily boron doping behaviors and characteristics in microwave plasma chemical vapor deposition (MPCVD) diamond films are investigated. The suppression on boron incorporation is observed with crystal quality improved when oxygen added into diamond doping process. A relatively low hole concentration is expected and verified by the Hall effects measurements due to the compensation effect of oxygen as a deep donor in diamond. Low acceptor concentration, high compensation donor concentration, and relatively larger acceptor ionization energy are then induced by oxygen addition, however, heavily boron-doped diamond film with high crystal quality can also be expected. The formation of oxygen-boron complex structure instead of oxygen substitution as indicated by X-ray photoelectron spectroscopy (XPS) results is suggested to be more responsible for the observed enhanced compensation effect due to its predicted low formation energy. Meanwhile, density functional theory (DFT) calculations show that the B-O complex structure are easily formed in diamond with a formation energy of -0.83 eV. This work provides a comprehensive understanding on the compensation of oxygen on the heavily boron-doped diamond.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Terahertz (THz) time-domain spectroscopy (THz-TDS) of polycrystalline MnCr<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> was performed at &amp;#60; 9 Tesla and low temperatures. A resonance absorption in the sub-THz range with linear blueshifts was observed as the magnetic field was increased 4 to 9 T. These magnetism-driven absorptions originated from a ferromagnetic resonance, which agrees with low-field electron spin resonance measurements and ferromagnetic resonance theory. The low-temperature g-factors of MnCr<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> were also obtained using THz-TDS. This work provides new insights into the spin dynamics of the in chromite spinel compounds in the THz region.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The effects of kinetic ions on the Double-Tearing Modes (DTM) are studied by using the gyrokinetic particle-in-cell (PIC) simulation code GEM with a gyrokinetic ion/fluid electron hybrid model. It is found that the ion kinetic effects can decrease the growth rate of the DTM. This effect is more significant for stronger coupling of DTM with smaller distance between the rational surfaces. Kinetic ions can also enhance the coupling effect between the two rational surfaces. Energy transfer analyses between particles and wave fields show that the stabilizing effect of kinetic ions comes mainly from the perpendicular magnetic drift of ions in the coupling region and around the outer rational surface.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>As an emerging branch in the area of flow control, hydrodynamic metamaterials have received considerable attention because of their novel flow control capabilities. In this review, we present prominent studies on hydrodynamic metamaterials in porous media, non-porous media, creeping flows, and non-creeping flows from several perspectives. In particular, for hydrodynamic cloaking metamaterials, we unify the descriptive form of transformation hydrodynamics for hydrodynamic metamaterials in porous and non-porous media by the hydrodynamic governing equations. Finally, we summarize and outlook the current shortcomings and challenges of current hydrodynamic metamaterials and propose possible future research directions, especially for microfluidics, exotic fluids, hydrodynamic cloaking in high Reynolds numbers, and turbulence.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In dielectrometry application, traditional analytical and numerical algorithms are hardly employed in complex resonant cavities. For a special kind of structure (rotating resonant cavity), the BOR-FEM is well employed to calculate the resonant parameters and dielectric parameters. In this paper, several typical resonant structures are selected for analysis and verification. Compared with the resonance parameter values in the literature and the simulation results of commercial software, the error of the BOR-FEM calculation is less than 0.9% and the solution time of a single time is less than 1s. The reentrant coaxial resonant cavities loaded with dielectric materials were analyzed using this method and compared with the simulation results, which showed a high accuracy. Finally, in this paper, the machined cavity with the established BOR-FEM method is successfully applied to the accurate measurement of the complex dielectric constant of dielectric materials. The test specimens were machined from PTFE, fused silica and Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, and the test results showed good agreement with the literature reference values.</jats:p>