In this paper, we have investigated a spin-wave-based Fabry-Pérot (FP) cavity using two air holes and notches embedded in a magnonic waveguide. Through micromagnetic simulations, we have demonstrated the spin-wave profile, as well as the transmission and reflection spectra of the FP type magnonic waveguide, by varying the distance between the center of holes and notches. We have introduced an analysis of the reflection spectra in an FP type magnonic waveguide, which is considerable and essential for the performance of magnonic integrated circuits. We have also presented a theoretical model to describe the transmission and reflection characteristics of the FP-type magnonic waveguide. Furthermore, active tuning of the resonance peak of the FP type magnonic waveguide by varying the external magnetic field has been demonstrated. Our proposed structure and its study may contribute to the development of magnonic integrated circuits for low-power computing and data processing in next-generation spintronic technologies.

We have studied ferromagnetic resonance in amorphous trilayers of Cox(Al0.70Zr0.30)1-x. The trilayer composition is such that the outer layers are ferromagnetic, with distinct resonance frequencies, while the spacer layer composition is nominally paramagnetic. We observe two precessional modes, acoustic and optical, and follow these as the interlayer exchange coupling, mediated by a strong proximity-induced magnetization in the spacer, is varied by changing the spacer layer thickness. We find that both the interlayer exchange coupling and the induced magnetization have an exponential decay profile within the spacer, with contrasting decay lengths of lambda IEC = 0.44 nm and lambda PIM = 3.1 nm. This contrast exposes the difference in decay length of spin stiffness, reflected in resonance experiments, and proximity-induced magnetization or polarizability in these amorphous trilayers, from static magnetization measurements.

The magnetic properties of amorphous thin films are shaped by inherent composition variations and magnetic proximity effects. Their magnetic properties can be tuned precisely with composition over a continuous range and their high resistance reduces shunting in spintronic systems. We examine the static and dynamic magnetic properties of amorphous magnetic thin films of Cox(Al0.7Zr0.3)1−x in the range $$0.60\le x<0.87$$ , with and without a purposely modulated composition. The Gilbert damping is very low but increases dramatically with decreasing Co content. Damping is also studied in a CoAlZr multilayer with alternating intrinsically paramagnetic and ferromagnetic layers, and a film with a continuously modulated composition, both showing low damping. The structural and magnetic depth profiles of the heterostructures are measured with XRR and PNR, where proximity-induced magnetization is observed in the paramagnetic constituents. The enhancement in magnetization and reduction in damping is equivalent to an increase in mean Co content of approximately 3.4 at% and 1.9 at% for the multilayer and continuously modulated film, respectively. The results demonstrate how composition modulations affect the static and dynamic properties of thin films and how the magnetic proximity effect reduces the impact of such variations in composition.

Increased recyclingRecycling share in aluminum productionAluminum production increases impurityImpurities content, resulting in a higher risk of stabilizing primary intermetallicsPrimary intermetallics. Having precise thermodynamic databases is crucial for forecasting and avoiding primaries during solidificationSolidification. In this work, we evaluate experimentally the Al-rich liquidus lines of Al–Ti and Al–Zr phase diagramsPhase diagram, using direct analysis of dilute molten alloys with laser-induced breakdown spectroscopySpectroscopy (LIBSLIBS). The liquid alloys are cooled at different rates and the concentration of dissolved elements is measured continuously using LIBSLIBS. The results at a cooling rateCooling rate of 1 °C/min show that concentration measurementsMeasurements follow the predicted liquidus lines of the phase diagramsPhase diagram, albeit not always in full agreement with available thermodynamic databases. LIBSLIBS measurementsMeasurements at faster cooling ratesCooling rate (5, 10, and 20 °C/min) show clear signs of nucleation undercooling, which depend on the cooling rateCooling rate and the initial composition of the alloys. Comparing the undercooling of different alloy concentrations at different cooling ratesCooling rate reveals that for the same mass composition in Ti or Zr, the Al3Ti-D022Al3Ti-D022 phase nucleates at lower undercooling than the Al3Zr-D023AlZr-D0 phase.

The Landau-Lifshitz-Gilbert equation for magnetization dynamics is recast into spinor form using the real-valued Clifford algebra (geometric algebra) of three-space. We show how the undamped case can be explicitly solved to obtain component-wise solutions, with clear geometrical meaning. Generalizations of the approach to include damping are formulated. The implications of the axial property of the magnetization vector are briefly discussed.

In this study, we investigate an innovative hybrid structure of silicon nanowires (SiNWs) coated with polyaniline (PANI):metal oxide (MO x ) nanoparticles, i.e., WO3 and TiO2, for respiratory sensing. To date, few attempts have been made to utilize such hybrid structures for that application. The SiNWs were fabricated using metal-assisted chemical etching (MACE), whereas PANI:MO x was deposited using chemical oxidative polymerization. The structures were characterized using Raman spectroscopy, X-ray diffraction, and scanning electron microscopy. The sensing characteristics revealed that the hybrid sensor exhibited a considerably better response than pure SiNWs:MO x and SiNWs:PANI. Such an enhancement in sensitivity is attributed to the formation of a p-n heterojunction between PANI and MO x , the wider conduction channel provided by PANI, increased porosity in SiNWs/PANI:WO3 hybrid structures, which creates active sites, increased oxygen vacancies, and the large surface area compared to that available in pure MO x nanoparticles. Furthermore, less baseline drift and increased sensor stability were established for the SiNWs structure coated with PANI:WO3, as compared to PANI:TiO2.

Thermodynamic calculations were employed to estimate activities and phase composition of the oxide layer for ternary dilute aluminumAluminum magnesium alloysMagnesium alloy; Al–Mg–M (M = Si, Zn, Zr, Ti, Be, or Ca). Previously, it has been reported that adding a ternary element modifies the vapor phase of Mg above the melt surfaceSurface. When Be or Ca was added, a strong reductionReduction of Mg partial pressure was recorded for small concentrations of the ternary element, in contrast with Si or Zn, where the effect was orders of magnitude smaller. This study aims to use Thermo-Calc simulationsSimulation to reveal the distributionDistribution of alloying elements between the liquid metal, oxide layer, and vapor phase and predict the phase composition of oxide layers. The variation of the Mg vapor phase can be linked, at least in part, to the formation of oxide layers on the melt surfaceSurface that may inhibit the diffusion of Mg.

We study the dependence of photo-spectral intensity on tri- and multilayers of SiO2/[SiGe [ dSiGe]/SiO2]N with repetitions N = 1 to 10 and thicknesses dSiGe=5-100 nm. Photocurrent analysis reveals a bimodal spectral feature. A comparison of the photocurrent analysis between tri- and multilayers shows that in the multilayer structures, the photo-spectral intensity increases with increasing repetition N. The change in intensity could then be further tuned by changing the thickness of the SiGe layers dSiGe. We attribute the change in intensity to an increase in tensile strain, along with increased Ge atomic concentration and reduced SiGe-nano cluster size.

In-situ laser-induced breakdown spectroscopy (LIBS) was used for measurements on molten aluminum alloys containing 0.6 wt pct magnesium in the melt temperature range 685 °C to 790 °C. With increasing melt temperature, an exponential growth of magnesium LIBS emission signals was observed, a phenomenon that has previously been attributed to the presence of Mg vapor above the melt surface. Here we show how this temperature dependence of the magnesium signal is affected by the presence of a second alloying element in the melt. For dilute ternary aluminum alloys Al–Mg–M, with M = Si, Zn, or Sn, the change in vapor-phase contribution to the Mg signal was found to be linearly correlated with the concentration of the additional alloying element but differing in sign and magnitude. Ternary alloys containing group-II alloying elements (M = Be, Ca, or Sr), known to inhibit oxidation of the melt, were also studied. The presence of these elements had a strongly reducing effect on the vapor-phase component of the Mg LIBS signal. We attribute this decrease to the formation of Be, Ca, or Sr-containing oxides that effectively inhibit the transport of Mg from the melt to the surface and into the vapor phase.

SiGe‐SiO2‐based structures present high interest for their high photosensitivity from visible to short‐wavelength infrared. Herein, two postdeposition annealing procedures, that is, rapid thermal annealing (RTA) and rapid‐like furnace annealing (FA), are compared. Both RTA and FA are performed at 600 °C for 1 min for SiGe nanocrystals (NCs) formation in SiO2 matrix in Si/SiO2/SiGe/SiO2 structures deposited by magnetron sputtering. The FA imitates RTA resulting in enhanced spectral response. X‐ray diffraction, transmission electron microscopy, and Raman spectroscopy are carried out showing Ge‐rich SiGe NCs with 11.3 ± 1.2 nm size for RTA and 9.4 ± 0.8 nm for FA. Photocurrent spectra for both structures show several peaks that are annealing dependent. The photocurrent intensity for FA samples is ≈7 times higher than RTA samples while cutoff wavelengths are slightly different, that is, 1365 nm for FA and 1375 nm for RTA. The FA structures show (at −1.5 V) over 4 A W−1 responsivity at 730 nm, 6.4 × 107 Jones detectivity at 735 nm, and 2.2 × 107 Jones at about 1210 nm. FA structures contain small SiGe NCs with incorporated residual strain, while RTA ones are formed of columnar SiGe NCs separated by SiGeOx amorphous regions and show increased tensile strain in the SiGe.

Accurate and fast breath monitoring is of great importance for various healthcare applications, for example, medical diagnoses, studying sleep apnea, and early detection of physiological disorders. Devices meant for such applications tend to be uncomfortable for the subject (patient) and pricey. Therefore, there is a need for a cost-effective, lightweight, small-dimensional, and non-invasive device whose presence does not interfere with the observed signals. This paper reports on the fabrication of a highly sensitive human respiratory sensor based on silicon nanowires (SiNWs) fabricated by a top-down method of metal-assisted chemical-etching (MACE). Besides other important factors, reducing the final cost of the sensor is of paramount importance. One of the factors that increases the final price of the sensors is using gold (Au) electrodes. Herein, we investigate the sensor's response using aluminum (Al) electrodes as a cost-effective alternative, considering the fact that the electrode's work function is crucial in electronic device design, impacting device electronic properties and electron transport efficiency at the electrode-semiconductor interface. Therefore a comparison is made between SiNWs breath sensors made from both p-type and n-type silicon to investigate the effect of the dopant and electrode type on the SiNWs respiratory sensing functionality. A distinct directional variation was observed in the sample's response with Au and Al electrodes. Finally, performing a qualitative study revealed that the electrical resistance across the SiNWs renders greater sensitivity to breath than to dry air pressure. No definitive research demonstrating the mechanism behind these effects exists, thus prompting our study to investigate the underlying process.

We present optimization of [(15 angstrom) Ni80Fe20/(5 angstrom) M]20 single crystal multilayers on (001) MgO substrates, with M being Cu, Cu50Pt50 and Pt. These superlattices were characterized by high resolution X-ray reflectivity (XRR) and diffraction (XRD) as well as polar mapping of important crystal planes. It is shown that cube on cube epitaxial relationship can be obtained when depositing at substrate temperature of 100 degrees C regardless of the lattice mismatch (5% and 14% for Cu and Pt, respectively). At lower substrate temperatures poly-crystalline multilayers were obtained while at higher substrate temperatures {111} planes appear at similar to 10 degrees off normal to the film plane. It is also shown that as the epitaxial strain increases, the easy magnetization axis rotates towards the direction that previously was assumed to be harder, i.e. from [110] to [100], and eventually further increase in the strain makes the magnetic hysteresis loops isotropic in the film plane. Higher epitaxial strain is also accompanied with increased coercivity values. Thus, the effect of epitaxial strain on the magnetocrystalline anisotropy is much larger than what was observed previously in similar, but polycrystalline samples with uniaxial anisotropy (Kateb et al. 2021).

We present a study of the effect of annealing amorphous ferromagnetic thin films of $\text{Co}_{0.85}(\mathrm{A}1_{0.7}\text{Zr}_{0.3})_{0.15}$ , post deposition. The annealing was done in vacuum with no applied magnetic field. We find that already at a relatively low annealing temperature of 130 $^{\circ} \mathrm{C}$ there is crystallite formation that introduces both structural and magnetic inhomogeneity. This does not affect the saturation magnetization strongly, but strongly affects the switching behavior and the overall effective anisotropy of the films. Further, there is a dramatic increase in magnetization damping. Thus, the annealing has a profound effect on both static and dynamic magnetic properties of the material. This is important to keep in mind for potential applications using these materials.

We report on Ge coated silicon nanowires (SiNWs) sensors synthesized with metal assisted chemical etching and qualify their functionality as human respiratory sensor. The sensors were made from p-type single-crystalline (100) silicon wafers using a silver catalysed top-down etching, afterwards coated by 50 nm Ge thin layer using a magnetron sputtering. The Ge post-treatment were performed by rapid thermal annealing (RTA) at 450 and 700 C degrees. The sensors were characterized by X-ray diffraction diffractogram and scanning electron microscopy. It is demonstrated that the sensors are highly sensitive as human breath detectors, with rapid response and frequency detect-ability. They are also shown to be a good candidate for human respiratory diseases diagnoses.

We report on the structure and electrical characteristics of silicon nanowire arrays prepared by metal assisted chemical etching (MACE) method, investigated by cross-sectional scanning electron microscopy (SEM) and high resolution X-ray diffraction (HR-XRD) methods. SEM micrographs show arrays of merged parallel nanowires, with lengths of 700 nm and 1000 nm, resulted after 1.5 min and 5 min etching time, respectively. X-ray reciprocal space maps (RSMs) around Si (004) reciprocal lattice point indicate the presence of 0D structural defects rather than of extended defects. The photoluminescence spectra exhibit emission bands at 1.70 eV and 1.61 eV, with intensity significantly higher in the case of longer wires and associated with the more defected surface. The transient photoluminescence spectroscopy reveals average lifetime of 60 os and 111 os for the two SiNW arrays, which correlate with a larger density of defects states in the latest case. The I-V characteristics of the nanowires, show a memristive behavior with the applied voltage sweep rate in the range 5-0.32V/s. We attribute this behavior to trap states which control the carrier concentration, and model this effect using an equivalent circuit. Photogeneration processes under excitation wavelengths in visible domain, 405 nm - 650 nm, and under light intensity in the range 20-100 mW/cm2 provided a further insight into the trap states.

We study the structure and temperature depen-dent electrical and magnetic properties of highly epitaxial $\mathrm{V}_{2}\mathrm{O}_{3}/\text{Ni}_{80}\text{Fe}_{20}$ layers grown on c-plane $\mathrm{A}1_{2}\mathrm{O}_{3}$ by direct current magnetron sputtering. We focus our attention on the structural and magnetic properties of the Ni 80 Fe 20 layer and their dependence on the deposition temperature. X-ray diffraction measurements reveal an epitaxial nature of the $\mathrm{V}_{2}\mathrm{O}_{3}$ layers with a (006) orientation. Electrical characterization of single layered $\mathrm{V}_{2}\mathrm{O}_{3}$ reveals a metal insulator transition at around $\sim 150$ K. All samples showed a strong epitaxial (1 1 1) peak showing that highly crystallized $\text{Ni}_{80}\text{Pe}_{20}$ layers can be deposited onto $\mathrm{V}_{2}\mathrm{O}_{3}$ at room temperature. Angular dependent magneto-optical Kerr effect characterization of the films reveals a uniaxial anisotropy in the films with a coercivity of the order of 1 Gauss. The first-order reversal curve method is used to analyze the magnetization reversal mechanism.

This study incorporates the structural and magnetic characterization of epitaxial Ni 80 Fe20 films grown by direct cur-rent magnetron sputtering on MgO(001) and MgO(001)||VN(001) substrates. A series of samples grown with different N 2 flow settings for the deposition of VN and similar permalloy deposition parameters was utilized to investigate the effect of morphological evolution and buffer layer induced strain on the magnetic properties of Ni 80 Fe20. X-ray diffraction analysis reveals an epitaxial nature of the VN(001) and Py(001) films grown on MgO substrates. Angular dependent magneto-optical Kerr effect characterization reveals a cubic anisotropy for Ni 80 Fe20 on MgO with a coercivity of ~0.8 Gauss along the easy directions. Incorpo-rating an epitaxial VN buffer, the structures showed a transition from a cubic to isotropic magneto-crystalline anisotropy with coercivity varying from 2.5 to 25 Gauss for Ni 80 Fe20 deposition on VN (with N2 varying from 5 to 12 sccm). The variation is attributed to the microstructural evolution of the Ni 80 Fe 20 to 3D structures along with an induced structural strain.

Silicon nanowires (SiNWs) are known to exhibit a large piezoresistance (PZR) effect, making them suitable for various sensing applications. Here, we report the results of a PZR investigation on randomly distributed and interconnected vertical silicon nanowire arrays as a pressure sensor. The samples were produced from p-type (100) Si wafers using a silver catalyzed top-down etching process. The piezoresistance response of these SiNW arrays was analyzed by measuring their I-V characteristics under applied uniaxial as well as isostatic pressure. The interconnected SiNWs exhibit increased mechanical stability in comparison with separated or periodic nanowires. The repeatability of the fabrication process and statistical distribution of measurements were also tested on several samples from different batches. A sensing resolution down to roughly 1m pressure was observed with uniaxial force application, and more than two orders of magnitude resistance variation were determined for isostatic pressure below atmospheric pressure.

In the present study, we demonstrate the measurement of resistivity tensor (rho) in the plane of a polycrystalline film of ferromagnetic permalloy (Py). To this end, conventional Hall-bar and a more recent extended van der Pauw methods were utilized for determining 2D rho in the film plane. The samples were prepared by normal incidence sputter deposition within an in situ magnetic field to induce in-plane uniaxial magnetic anisotropy in the film. Since rho might be affected by the internal magnetization of the film, we performed measurements by rotation of a saturating magnetic field in the film plane. Both methods indicate that the average resistivity is lower along the magnetic easy axis of the film compared to the hard axis. Since X-ray diffraction results indicated no dominating texture in the film, we concluded that there is a correlation between uniaxial magnetic axes and principal resistivity axes. This is an important finding that allows determining the direction of magnetic anisotropy axes without magnetometry. The results also verify atomic or pair ordering to be the origin of uniaxial magnetic anisotropy in the Py since resistivity is sensitive to the level of order in solids. The extended van der Pauw utilized here can be easily performed on the as-deposited samples, which is of practical interest.

We investigate the photoluminescence properties of structures comprising of Si 1-x Ge x nanoparticles (NPs) within SiO 2 , GeO 2 , TiO 2 and Ta 2 O 5 oxide matrices. Of the investigated structures, it was observed that the structures with GeO 2 and TiO 2 matrices provide increased spectral response (at ~907 and 844 nm respectively) and increased PL intensity. The improved PL characteristic have been attributed to increased diffusion barrier against oxygen which otherwise would result in formation of unwanted oxide at the film-oxide interface, thereby deteriorating the optical properties.