Performance and lifetime analysis of electrospray thrusters requires accurate knowledge of the mass and charge distributions of the plume. Mass flux and current density distributions were measured for a single capillary electrospray emitter using EMI-Im and found to be substantially different across a wide range of flow rates and emission voltages. Mass flux measurements yield an n∼3 super-Gaussian

Solution pH is a significant parameter that affects the electrical characteristics of gas–liquid discharges and thus potentially produces different plasma chemistries for different plasma-engineered applications. In this study, the discharge characteristics and long-lived aqueous reactive species under different initial pH conditions were investigated. It was found that the discharge contained three

We present an experimental study of nanosecond high-voltage discharges in a pin-to-pin electrode configuration at atmospheric conditions operating in a single-pulse mode (no memory effects). Discharge parameters were measured using microwave Rayleigh scattering, laser Rayleigh scattering, optical emission spectroscopy enhanced with a nanosecond probing pulse, and fast photography. Spark and corona

Ablation of a graphite anode by an arc is used to produce nanoparticles. The flow of the ablated carbon particles hampers access of plasma ions to the anode sheath. While the ablation rate is low, ions are still capable of reaching the sheath, where they counter the electric charge of electrons, anode voltage drop is negative. At ablation rates higher than some critical value, the flow of the ablating

Aluminum nitride is piezoelectric and exhibits spontaneous polarization along the c axis, but the polarization cannot be switched by applying an electric field. Adding Sc to AlN enhances the piezoelectric properties and can make the alloy ferroelectric. We perform a detailed first-principles analysis of spontaneous and piezoelectric polarization. Comparisons between explicit supercell calculations

This work uses density-functional theory to model the magnetic properties of bismuth-based perovskite oxides under epitaxial strain. We augment the known transition in BiFeO3 between rhombohedral-like and tetragonal-like phases occurring at 4.2% compressive epitaxial strain with the variation in magnetic behavior near this boundary. This phase boundary coincides with a transition from G- to C-type

Nuclear magnetic resonance techniques are widely used in the natural sciences but they lack sensitivity. Therefore, large sample volumes or long measurement times are necessary. In this work, we investigate the polarization of bulk 13C nuclei in a diamond above the thermal equilibrium at room temperature. Previously studied mechanisms utilize direct coupling to nitrogen vacancy centers or the additional

Orthorhombic α−MoO3 is a layered oxide with various applications and with excellent potential to be exfoliated as a 2D ultra-thin film or monolayer. In this paper, we present a first-principles computational study of its vibrational properties. Our focus is on the zone center modes, which can be measured by a combination of infrared and Raman spectroscopy. The polarization dependent spectra are simulated

The Hamiltonian size reduction method or the mode space method applicable to general heterogeneous structures is developed in this work. The effectiveness and accuracy of the method are demonstrated for four example devices, such as GaSb/InAs tunnel field effect transistors (FETs), MoTe2/SnS2 bilayer vertical FETs, InAs nanowire FETs with a defect, and Si nanowire FETs with rough surfaces. The Hamiltonian

In this paper, the occupancy of sidewall surface states having a clear signature in the performance of AlGaN/GaN-based self-switching diodes (SSDs) is analyzed using a semi-classical Monte Carlo (MC) simulator in a wide temperature (T) range, from 100 to 300 K. Experimental I–V curves show an unusual current decrease at low temperature attributed to surface trapping. The dependence on T of the negative

A theoretical model and a finite element (FE) model are proposed to evaluate the effect of high temperature on the sound absorption performance of cylindrically perforated porous materials. The theoretical model is established by applying the double porosity theory, in which the perforated porous material is considered as a combination of the porous material matrix and the cylindrical perforation.

Controlling magnetic damping lies at the heart of spintronic applications. In particular, manipulating the radiative damping of magnons is important for the emerging dissipative magnon–photon coupling and, therefore, opens up possibilities for advanced hybrid magnonic devices, nonreciprocal transmission, and topological information processing. The materials or structures that produce magnon modes can

We propose the design of a tubular phononic crystal (TPC) for the purpose of sensing the physical properties of a liquid filling the hollow part of the tube. The TPC is constituted by a periodic repetition of washers along a hollow pipe with the advantage of avoiding any perturbation of a flowing fluid by any element inside the tube. Using finite element simulations, we demonstrate the existence of

Quasi-static uniaxial tension and compression, three-point bending, and Hopkinson bar measurements have been carried out on low-porosity Al/Ni compacts (pressed powders) as well as compacts of the constituent Al and Ni. Concurrently, mesoscale material point method (MPM) simulations of fully resolved Al, Ni, and Al/Ni compact microstructures and engineering scale MPM simulations of homogenized Al/Ni

The synthesis of transfer-free graphene is necessary for expanding its industrial applications. Although the direct synthesis of graphene on the insulating substrate via a metal sacrificial film was reported, the growth mechanism of transfer-free graphene still remains to be studied. Herein, a detailed synthesis model of graphene grown from different carbon sources has been established to help in selecting

Bulk gallium oxide (Ga2O3) has been widely used in lasers, dielectric coatings for solar cells, and deep-ultraviolet transistor applications due to the large bandgap over 4.5 eV. With the miniaturization of electronic devices, an atomically thin Ga2O3 monolayer has been unveiled recently, which features an asymmetric configuration with a quintuple-layer atomic structure. The superior stability, the

Measurements of conductance fluctuations in undoped hydrogenated amorphous germanium (a-Ge:H) find power spectra that vary with inverse frequency (1/f) that are characterized by non-Gaussian statistics. The non-Gaussian aspect of the 1/f noise is reflected in (1) histograms of the noise power per octave that are described by lognormal distributions, (2) power-law second spectra, and (3) strong correlations

This work investigates the conductivity and structure of nanocrystalline CaF2 films grown at 200 °C by thermal evaporation. The in-plane conductivity is enhanced by several orders of magnitude compared to lightly doped bulk samples of CaF2, which independently confirms the finding of a previous work [Modine et al., J. Appl. Phys. 74, 2658 (1993)]. Upon heating above 200 °C, the enhancement is partially

Electrostatic doping-assisted phonon softening has been intensively investigated in semiconducting transition metal dichalcogenides (TMDCs), in which strong electron–phonon interactions can be achieved in thin layers. Though electron–phonon coupling plays an important role in structure phase transitions for metallic 2H-TaX2 (X = S, Se), it has been rarely studied under electrostatic doping. Here, the

The effects of ion irradiation on the surface and the subsurface of synthetic diamonds were characterized by using optical microscopy, atomic force microscopy, Raman spectroscopy, x-ray reflectivity, electron backscatter diffraction, and resistivity measurements. Irradiation experiments with 14 MeV Au6+ ions with fluences up to 2.4×1015 ions/cm2 were carried out on synthetic single crystal diamonds

Surface traveling waves (STWs) contribute greatly to non-specular scattering, but their scattering and attenuation characteristics in an absorbing coating are unclear. Thus, the scattering peak angular location and the electromagnetic (EM) loss of the STWs are calculated. The results show that the thickness of an absorbing coating should be appropriate to achieve a large EM loss in wide frequency bandwidth

Atomic layer deposition is a powerful technique for achieving atomic-level control in the deposition of thin films and nanoparticles. The ultrathin noble metal films can be applied in many functional devices, but it is a challenge to obtain such films since the island growth mode generally happens instead of the layer growth mode. In this work, the nucleation and growth of platinum on Si, Al2O3, Au

We investigate the effects of oxygen on the thermal diffusion of germanium atoms, implanted inside a thermally grown SiO2 layer, during high temperature processes (1100 °C, 60 min). The impact of the presence of oxygen on Ge diffusion is studied as a function of its origin, as it can come either from the annealing atmosphere (extrinsic source) or from the SiO2 matrix itself (intrinsic source). 18O

Anomalous growth rate reduction and associated composition divergence with increasing aluminum flux in m-plane AlGaN grown by plasma-assisted molecular beam epitaxy at low temperature (565 °C) are observed and investigated. We find that the AlGaN growth rate under conventional gallium-rich conditions decreases rapidly with increasing aluminum flux, contrary to expectations. Moreover, the aluminum fraction

Electron traps generated during the reactive ion etching (RIE) process in n-type 4H-SiC are investigated using the deep-level transient spectroscopy technique and isothermal capacitance transient spectroscopy (ICTS) technique. Two electron traps of the Z1/2 center (EC−0.64eV) and the EH3 center (EC−0.74eV) are detected in the RIE-etched sample by ICTS measurement at 300 K. A method is proposed to determine

In SiN/AlGaN/GaN heterostructures, the evaluation of interface charges at the SiN/AlGaN and AlGaN/GaN interfaces is crucial since they both rule the formation of the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface. In this paper, we conducted a thorough analysis of the gate-to-channel capacitance CGC(VG) and of the drain current ID(VG) over a gate voltage VG range enabling the depletion

Magnonics is now an attractive field which focuses on the dynamic characteristics of magnons, a kind of quasiparticles in magnetic media, and attempts to apply magnons for functional devices. In order to construct magnon-based devices, it is necessary to fabricate materials with specific and tunable magnon bands and bandgaps. Skyrmion-based magnonic crystal is one of the most suitable materials which

Significant progress has been made in answering fundamental questions about how and, more importantly, on what time scales interactions between electrons, spins, and phonons occur in solid state materials. These complex interactions are leading to the first real applications of terahertz (THz) spintronics: THz emitters that can compete with traditional THz sources and provide additional functionalities

We report the symmetry-dependent intensity–noise correlation and the intensity-difference squeezing of spontaneous parametric four-wave mixing (SP-FWM) and fluorescence (FL) hybrid signals from the different phases [hexagonal (H) + tetragonal (T), T + H] of Pr3+: YPO4 and Eu3+: YPO4 crystals. The competition between FL and SP-FWM in hybrid signals determines the amplitude and hybrid line shape of the

Active tunability of phonon dispersion and spontaneous emission (SE) still remain open owing to its exciting application potential. In this study, multilayer graphene and hexagonal boron nitride (hBN) combined with the Ge2Sb2Te5 (GST) functional substrate are proposed to obtain tunable hyperbolic plasmon–phonon dispersion and SE. Results indicate that GST phase change has a profound impact on hyperbolic

Based on the pulsed current interception of underwater discharge, the characteristics of the steepness of electrohydraulic shock waves (EHSWs) and the peak value still increasing slowly with the electrical energy injection after the acceleration expansion phase of the plasma channel are investigated. The one-dimensional “piston” model of the EHSW generation is improved, and the calculation method for

In this study, ferroelectric Pb(Fe1/2Nb1/2)O3 with an antiferromagnetic polymorph at and below 150 K was converted into a room-temperature magnetoelectrically active multiferroic with soft ferromagnetism by disrupting the existing antiparallel spin alignment of Fe ions through the heavy replacement of Fe by Ni. To maximize the induced soft-ferromagnetic properties and the consequent nonlinear magnetoelectric

The magnetic properties of uranium nitride (UN) surfaces are not well understood experimentally or computationally but they have a significant effect on UN performance as a nuclear fuel. We investigated ferromagnetic (FM), antiferromagnetic (AFM), nonmagnetic (NM), and three hybrid magnetic structures of the most stable UN surface (100). To account for electron correlation and metastability, a U-ramp

We report on the observation of the Shubnikov–de Haas oscillation in a polycrystalline ZnO/CdO heterostructure grown on a silicon substrate by a spray pyrolysis technique in temperatures below 6 K. From the analysis of these quantum oscillations, we obtained the cyclotronic effective mass, the 2D carrier concentration, and the thickness of the two-dimensional electron gas in the interface of the two

The influence of the facet trace region in the 4H-SiC substrate on the glide and propagation behaviors of basal plane dislocations (BPDs) in a 4H-SiC homoepitaxial layer was investigated using x-ray topography, high-resolution x-ray diffraction, and micro-Raman scattering spectroscopy. The facet trace region in the substrate, which has a higher nitrogen doping concentration than the other regions in

We study the generation and control of the microwave (MW)-induced reverse saturable absorption (RSA) and optical limiting (OL) in a three-level pump-probe V-type quantum system. It is shown that the saturable absorption switches to the RSA by applying the MW field to the transition between two upper levels. Moreover, it is demonstrated that the RSA and the induced OL threshold are controlled by either

We report on enhanced third-harmonic generation based on intersubband transitions in an asymmetric InxGa1-xN/InN double quantum well. We give a comprehensive account of the influences of different structural parameters such as doping concentration, thickness of layers, and indium mole composition of barriers on the intersubband transition quantities and then their nonlinear response. The conduction

A coded aperture is used to demonstrate emission spectroscopy from multiple one-dimensional measurement locations simultaneously with a single camera. The coded aperture mask has several columns of periodic apertures, each with a unique spatial frequency. Light transmitted through all mask columns is detected through an imaging spectrometer. Dispersed light from the various mask columns overlaps on

The CO2 laser material interaction is commonly used for thermal treatments and processing of fused silica glasses. As the laser pulse duration decreases down to a few tens of microseconds, the heat-affected depth in the material decreases up to the point where it has the same magnitude as the laser radiation penetration depth, which is an interesting operating point for applications that require minimal

In wall-less Hall thrusters, the ionization of the propellant and the acceleration of the ions occur outside the thruster [S. Mazouffre, S. Tsikata, and J. Vaudolon, in 50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference (American Institute of Aeronautics and Astronautics, Cleveland, OH, 2014)]. This reduces interactions between the plasma and the thruster parts as compared to conventional annular

Cold atmospheric plasmas have great application potential due to their production of diverse types of reactive species, so understanding the production mechanism and then improving the production efficiency of the key reactive species are very important. However, plasma chemistry typically comprises a complex network of chemical species and reactions, which greatly hinders identification of the main

Imprint, the preferential orientation of the polarization of a ferroelectric device subjected to elevated temperatures, is a primary reliability concern afflicting data retention in ferroelectric RAM. In this paper, we demonstrate Preisach-based hysteresis modeling, which can be used to predict imprint behavior in ferroelectric thin films. A method was developed for capturing imprint in the context

After obtaining Ti3C2 MXene structures terminated with O, S, Se, F, Cl, and Br, we calculate the energy barrier for Li-ion diffusion on the surface of each MXene, being the first to report on the Li-ion diffusivity in Cl and Br terminated Ti3C2. We find that the Ti3C2Cl2 MXene has the lowest diffusion barrier, substituting the Ti3C2S2 reported in the literature so far. In addition, a study on the adsorption

Large single crystals of rare-earth calcium oxoborates RCa4O(BO3)3 with R=Er, Y, Dy, Gd, Sm, Nd, La (RCOB) were grown by the Czochralski method. Complete sets of dielectric, piezoelectric stress, and elastic stiffness coefficients of the RCOB crystal species were determined at ambient conditions using a combination of resonant ultrasound spectroscopy and the substitution method. The results are inherently

Metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) are two versatile growth techniques that can readily produce multilayer structures with atomic-level precision control, which have found broad applications in technology. However, compared to MBE, MOCVD growth involves the surface reaction of metal-organic precursor compounds, which changes during film deposition. Consequently

The scientific study of plasma discharges and their material interactions has been crucial to the development of semiconductor process engineering and, by extension, the entire microelectronics industry. In recent years, the proliferation of the big data business model has led to heightened interest in technology candidates with the potential to supplant CMOS architectures in critical metrics such

Persistent phosphors are luminescent sources based on crystalline materials doped with rare-earth or transition metal cations able to produce light after the excitation source vanishes. Although known for centuries, these materials gained renewed interest after the discovery of Eu2+,RE3+ co-doped aluminates and silicates in the late 1990s due to their unprecedented afterglow properties. In contrast

In this Tutorial, we give a pedagogical introduction to Majorana bound states (MBSs) arising in semiconducting nanostructures. We start by briefly reviewing the well-known Kitaev chain toy model in order to introduce some of the basic properties of MBSs before proceeding to describe more experimentally relevant platforms. Here, our focus lies on simple “minimal” models where the Majorana wave functions

There are many advantages of LEDs in energy and environmental conservation, but their short life in many outdoor applications prompt a necessity to have a detailed understanding of their degradations to prolong their lifetime, which can also conserve LED material and even expand their applications. Using ab initio density functional theory formulation, we identify the detail paths of the LED degradation

In the recent past, high-refractive index nano- and micropillars have been widely used for significantly enhancing the fluorescence properties of quantum emitters embedded within the pillar. However, a complete study of the electromagnetic dynamics and nanophotonics of single-photon emission inside the high-refractive index nanopillars is currently missing. In order to design nano- and micropillars

In this paper, we investigate the formation of a photonic terajet and tune its optical properties using the high-resolution finite-difference time-domain method. A Dirac semimetal is coated onto the surface of a dielectric rod and illuminated with an incident plane wave. The refractive index of the Dirac semimetal can be modulated by changing its Fermi energy. It was demonstrated that the presence

The article reports the excitation of a helical argon atmospheric pressure plasma jet using a pulse-modulated 13.56 MHz radio frequency (RF) power source. This helical structure is observed in open ambient air, which is far different from the conventional conical shape. This helical structure originates due to the periodic pressure variation in the discharge region caused by pulse-modulated RF (2 kHz

A numerical model for simulating current–voltage characteristics (IVCs) of reactive magnetron discharges is developed. The model is built on the basis of equilibrium equations describing the steady state of reactive magnetron sputtering processes. This modeling technique allows an analytical expression of IVCs with a pair of parametric equations, which are computationally convenient. This approach

Lanthanum hexaboride (LaB6) hollow cathodes have demonstrated a capability for long life operation, which is critical to many space exploration missions. Thermal characterization of LaB6 hollow cathodes has revealed lower than expected electron emitter temperatures when the cathode reaches a steady state. This phenomenon is observed at discharge currents ranging from 5 to 35 A and xenon mass flow rates

The nitrogen-vacancy (NV) center has enabled widespread study of nanoscale nuclear magnetic resonance (NMR) spectroscopy at low magnetic fields. NMR spectroscopy at high magnetic fields significantly improves the technique’s spectral resolution, enabling clear identification of closely related chemical species. However, NV-detected NMR is typically performed using AC sensing through electron spin echo

Commercial high-Tc superconducting (HTS) coated conductors exhibit asymmetric Ic(B,θ) characteristics, where B presents a DC magnetic field and θ is defined as the angle between an applied magnetic field and the normal component of the superconductor plane. The asymmetric Ic(B,θ) characteristics have a non-trivial influence on the dominant loss component, magnetization loss, of various HTS applications

We excite the gyrotropic mode of a magnetic vortex and observe the resulting effect on the spin state of a nearby nitrogen-vacancy (NV) defect in diamond. Thin permalloy disks fabricated on a diamond sample are magnetized in a vortex state in which the magnetization curls around a central core. The magnetization dynamics of this configuration are described by a discrete spectrum of confined magnon

Ferromagnetic (FM) interlayer exchange coupling of ion-beam sputtered Fe/Ge multilayers was investigated by off-specular polarized neutron scattering measurements. We observed a monotonously growing correlation of magnetic moments in the out-of-plane direction with decreasing Ge thickness. The magnetic properties of the multilayers with and without the FM interlayer exchange coupling agree well with

We introduce a wide-field magneto-optical microscope to probe magnetization dynamics with femtosecond temporal and sub-micrometer spatial resolution. We carefully calibrate the non-linear dependency between the magnetization of the sample and the detected light intensity by determining the absolute values of the magneto-optical polarization rotation. With that, an analytical transfer function is defined

We have investigated the magnetization dynamics in single and trilayer circular permalloy nanodots with a diameter of 120 nm using broadband ferromagnetic resonance spectroscopy. For single-layer nanodots, two well-separated modes near the saturation field, a high-frequency center mode due to excitations at the center of the nanodots and a low-frequency edge mode due to the inhomogeneous effective