Shape Of Hysteresis Loop Research Articles

Stress-Induced Transformations of Polarization Switching in CuInP2S6 Nanoparticles

Using the Landau-Ginzburg-Devonshire approach, we study stress-induced transformations of polarization switching in ferrielectric CuInP2S6 nanoparticles for three different shapes: a disk, a sphere, and a needle. Semiconducting properties of a nanoparticle are modeled by a surface charge layer, whose effective screening length can be rather small due to the field-effect. We reveal a very strong and unusual influence of hydrostatic pressure on the appearance of polarization switching in CuInP2S6 nanoparticles, hysteresis loops shape, magnitude of the remanent polarization, and coercive fields, and explain the effects by the anomalous temperature dependence and "inverted" signs of CuInP2S6 linear and nonlinear electrostriction coupling coefficients. In particular, by varying the sign of the applied pressure (from tension to compression) and its magnitude (from zero to several hundreds of MPa), quasi-static hysteresis-less paraelectric curves can transform into double, triple, pinched, or single hysteresis loops. Due to the sufficiently wide temperature and pressure ranges of double, triple, and pinched hysteresis loop stability (at least in comparison with many other ferroelectrics), CuInP2S6 nanodisks can be of particular interest for applications in energy storage (in the region of double loops), CuInP2S6 nanospheres maybe suitable for dynamic random access multibit memory, and CuInP2S6 nanoneedles are promising for non-volatile multibit memory cells (in the regions of triple and pinched loops). The stress control of the polarization switching scenario allows the creation of advanced piezo-sensors based on CuInP2S6 nanocomposites.

Shear capacity estimation of core steel tube reinforced PCCC column-beam interior joint under quasi-static load

In this study, the quasi-static tests were conducted on 13 core steel tube (CST) reinforced PVC-CFRP confined concrete (PCCC) column-beam interior joints. Distinct shear failure occurred in all joint specimens. The load-displacement hysteresis curves appeared pinching phenomenon, and the shape of hysteresis loops gradually deformed from shuttle to arch and finally changed to reverse S shape. The overall shape of hysteresis curves were relatively full, demonstrating that the joints had favorable seismic performances and energy dissipation capacity. The strain development law of materials in the joint area in the process of stress was clarified. The increment of joint stirrup ratio ([Formula: see text]), axial compression ratio ([Formula: see text]), column reinforcement ratio ([Formula: see text]) or beam reinforcement ratio ([Formula: see text]) improved the calculated shear capacity of the joints. The calculated shear capacity increased first and then decreased slightly as the diameter-thickness ratio of CST ([Formula: see text]) increased. In comparison, spacing of CFRP strip had little impact on the calculated shear capacity. Additionally, the concrete strength enhancement coefficient ([Formula: see text]) and joint stirrup utilization coefficient ([Formula: see text]) were introduced respectively to modify the shear capacity of concrete and joint stirrups, and a simplified formula for predicting the shear capacity of CST reinforced PCCC column-beam interior joints under quasi-static load was proposed. The predicted results agreed well with the test data.

DYNAMICS NOISE BEHAVIORS ON MAGNETO-OPTICAL KERR EFFECT MEASUREMENT SYSTEM

Nowadays, computer and data processing industry are moving to nanomagnetic devices technology. One of the common measurement systems to observe nanomagnetic device are magneto optical Kerr effect and Faraday effects. The magneto-optical Kerr effect measurement system has been fabricated and precision noise measurement configuration was observed. A light intensity, which was reflected by thin film nanomagnetic surface, was measured accompany with its noise level. The lock-in amplifier was attached to pick up hysteresis signal and low noise level. Different frequency of lock-in amplifier was carried out to observe dynamics noise level behavior. Interestingly, we found butterfly shape noise corresponding to hysteresis loop shape. Furthermore, noise behavior with 0.94 scaling exponent, was found with respect to lock-in amplifier frequencies suggested that measuring in low frequency became more challenging.

Influence of Ni2+ substitution by Co2+ on the morphology and magnetic properties of single domain CoαNi0.9-αZn0.1Fe2O4 nanoparticles

This study presents the effect of Ni2+ substitution by Co2+ on the structure, morphology and magnetic properties of CoαNi0.9-αZn0.1Fe2O4 nanoparticles calcined at different temperatures. Fourier-transform infrared spectroscopy revealed the presence of Fe-O, Co-O, Zn-O and Ni-O bonds in samples calcined at 200 °C, while the presence of the characteristic bonds of the SiO2 confirmed the embedding of CoαNi0.9-αZn0.1Fe2O4 at all calcination temperatures. Single phase poorly crystalline ferrite for samples calcined at 400 °C and ferrite accompanied by traces of Fe2SiO4 and SiO2 for samples calcined at high temperatures (800 and 1200 °C) were identified. The dependence of X-ray diffraction parameters on the Co2+ content of nanoparticles was also investigated. The increase in Co2+ content and calcination temperature led to crystallite growth from 4 to 43 nm, while the porosity decreased with the increase in Co2+ content and calcination temperature. The magnetic properties of the rectangular shape nanoparticles evolved proportionally with the particle size. The magnetization, coercivity and magnetocrystalline anisotropy increased with the increase in Co2+ content and calcination temperature. The shape of hysteresis loops indicated a superparamagnetic-like behavior of the nanoparticles calcined at 400 °C and a ferrimagnetic-like behavior at higher calcination temperatures (800 and 1200 °C). These features make the obtained nanoparticles attractive candidates for various technical applications.

Perpendicular Magnetic Properties on hcp-Co<sub>80</sub>Pt<sub>20</sub> Stacked Films with Oxide Seed Layers

The influence of oxide seed layers on the magnetic properties and crystalline structures of hcp-Co80Pt20 perpendicular magnetic thin films were investigated for magneto-optical chemical and biological sensing system. Cr-O, Al-doped ZnO (AZO) and Al2O3 films were used as the oxide seed layers. The Cr-O layer was most effective to improve the perpendicular magnetic properties of Co-Pt. The Cr-O seed layer produced the largest values of the interfacial perpendicular magnetic anisotropy (KS) and perpendicular magnetocrystalline anisotropy (KV). The investigation in the crystalline and chemical bonding conditions suggested that the both perpendicular magnetic anisotropies were originated from the interaction of Co and oxide at the Co-Pt/Cr-O interface. The improvements of KS and KV on the Cr-O seed layer are attributed to the hybridization of Co-3d and O-2p orbits and the hcp(001)-CoPt crystal growth with self-orientation, respectively. We also demonstrated the magneto-optical cavity effect on the Co-Pt perpendicular magnetic stacked films with the Cr-O intermediate layer. The stacked films indicated a large magneto-optical response by optical interference and good perpendicular magnetic properties with an ideal square shaped hysteresis loop.

An Overview of Complex Instability Behaviors Induced by Nonlinearity of Power Electronic Systems with Memristive Load

The proposal of the memristor, considered as the fourth basic circuit element, suggests a new possibility for the design of high-performance power electronic systems. However, it also brings new challenges. At present, more and more electrical equipment and systems have demonstrated that their external characteristics can exhibit “8”-shaped hysteresis loops and can be regard as memristive equipment and systems. In order to satisfy the requirements of controllability, flexibility, efficiently, and so on, most memristive equipment and systems are not directly connected to the power grid but instead obtain their own required powering through various forms of power electronic converters. Note that memristive loads are distinctive and demonstrate unique nonlinear behaviors. Similarly, there can be nonlinearity from the resistor (R), inductor (L), or capacitor (C) load, but there is no combination of only R, L, and C that could produce memristive characteristics. In particular, the memristance of memristive devices changes continuously during the operation process; in addition, practical power electronic systems composed of memristive devices and power supplies have strong nonlinear characteristics, which are more likely to result in various complex behaviors and are not conducive to the stable operation of the systems. Therefore, exploring complex instability behaviors of power electronic systems with strong nonlinearity in depth is necessary for better protection and utilization of memristive devices. This paper provides an outline of the status of research on complex behaviors of power electronic systems with memristive load; it is expected to provide guidance for the study of complex behavior of strongly nonlinear systems.

Method Selection for Analyzing the Mesopore Structure of Shale—Using a Combination of Multifractal Theory and Low-Pressure Gas Adsorption

Nitrogen adsorption experiments have been extensively applied to shale pore structure research and evaluation. The pore structure can be quantitatively characterized in accordance with the nitrogen adsorption–desorption isotherm using various calculation models, whereas the results obtained using different models can more effectively indicate the pore characteristics of shale remains unclear. Further, there has not been any unified process in the optimization of calculation models for pore size distribution (PSD). In this study, the Barret–Joyner–Halenda adsorption (BJH-AD) and BJH desorption (BJH-DE) models were used with Longmaxi Formation shale as an example. Subsequently, the density functional theory (DFT) calculations were conducted on different shale lithofacies samples. Next, the pore structure parameters and heterogeneity obtained using different models were compared, and the consistency parameters of different models were obtained in accordance with Cronbach’s alpha. The results indicated that the pore structure parameters obtained using the BJH-AD model were underestimated since the macroscopic thermodynamic theory was not applicable to this study. The DFT model showed multiple peaks in the range of 1–10 nm, whereas the BJH-DE model had a significant artificial peak in the range of 3.8 nm due to the tensile strength effect, thus suggesting that the DFT model is more capable of characterizing the pores with a pore size 10 nm lower than the BJH model. The PSD curves generated using the three models exhibited multifractal characteristics, whereas the results of the heterogeneity achieved using different models were different. Moreover, the consistency of the results of different models can be studied in depth by combining Cronbach’s alpha with various heterogeneity parameters. The DFT model exhibited high consistency in pore structure parameters and pore heterogeneity, thus suggesting that the DFT method of N2 is the optimal physical adsorption data analysis method in the shale mesoporous range. Accordingly, the nitrogen adsorption curve, the hysteresis loop shape, multifractal parameters, and Cronbach’s alpha were integrated to generate a working flow chart of the nitrogen adsorption model for N2-adsorption-model optimization.

Joint Intercalation of Ultrathin Fe and Co Films under a Graphene Buffer Layer on a SiC(0001) Single Crystal

The joint intercalation of Co and Fe atoms under a graphene buffer layer synthesized on a SiC(0001) single crystal has been studied. Intercalation has been performed by means of the alternating deposition of ultrathin Fe and Co metal films on the substrate heated to 450°C with the subsequent heating to 600°C in 15 min. It has been shown that Co and Fe atoms under these conditions are intercalated under graphene, forming compounds with silicon and with each other. The existence of a magnetic order in the system up to room temperature has been demonstrated using a superconducting quantum interferometer. A possible stoichiometry of the formed alloys has been analyzed using data on the shape and magnitude of hysteresis loops. In addition, it has been found that Fe and Co in the system exposed to the atmosphere are not oxidized. Thus, graphene protects the formed system. This study makes contribution to the investigation of graphene in contact with magnetic metals and promotes its application in spintronic and nanoelectronic devices.

Triple and double hysteresis loops in relaxor ferroelectric PMN-0.28PT crystals

The evolution of the dielectric hysteresis loops shape during heating of PMN-0.28PT single crystals possessing rhombohedral symmetry at room temperature was studied in the temperature range from room temperature to 200 °C. Revealed formation of the triple and double dielectric hysteresis loops in the relaxor phase upon switching by an electric field was explained by the influence of depolarizing fields arising at the interface of non-polar inclusions, and by the ineffective screening of polar clusters forming during transition through a percolation threshold, correspondingly. Further size decrease in the polar clusters due to heating led to their transformation to polar nanoregions.

A 300 MHz MOS-only memristor emulator

MOS-only memristor emulators that work solely on the intrinsic capacitors of the transistors can have a high frequency operation feature and a low occupied chip area. This paper presents a memristor emulator consisting of two MOSFETs (i.e., M0 and M1) without any external elements and power supplies except for grounded M1’s source and body. When M0 and M1 are p-channel/n-channel MOSFETs, the proposed memristor emulator is named PMME/NMME. The post-simulation i−v curves of PMME/NMME exhibit pinched hysteresis loop shapes before the frequency of their sine inputs increases to 300 MHz. The occupied layout area of PMME/NMME is 1.8 * 2.57 μm2 in the Cadence design environment with 65 nm CMOS process. Furthermore, four stateful logic circuits based on PMMEs and NMMEs are presented. The feasibility of the proposed memristor emulator is verified with discrete p-channel MOSFETs of CD4007.

Manipulation of magnetic and structure properties of Ni2FeSi glass-coated microwires by annealing

In the current work, we demonstrate that the magnetic and structural properties of Ni2FeSi glass-coated microwires are strongly dependent on annealing conditions. A noticeable change in the magnetic and structural properties has also been compared to as- prepared samples. Annealing conditions increase the crystalline phase content from 34% to 72% for annealing duration 1 h and 6 h, respectively. While as- prepared samples show square hysteresis loops for a wide range of measuring temperatures, annealed samples show inclined hysteresis loops shape. Additionally, a marked increase in coercive and magnetic anisotropy fields has been observed for annealed samples as compared to as- prepared ones at and below room temperature. Meanwhile, highly reduced magnetic remanence was measured in the as-prepared samples. Temperature dependence of the coercivity shows anomalous behavior for as-prepared and annealed samples as well. An increase in the magnetization of the metallic nuclei of Ni2FeSi glass-coated observed in annealed microwire has been attributed to the internal stresses relaxation caused by annealing. The anomalous magnetic behavior at low temperature is due to the coexistence of ordered and disordered phases induced by annealing conditions. The difference in magnetization behavior, remanence, and coercivity values for Ni2FeSi glass-coated microwires samples indicates the influence of internal stresses created by the presence of the glass coating. These findings reveal the sensitivity of Heusler-based glass-coated microwires to temperature and annealing conditions, which will open the door to the design of spintronic devices and sensing applications.

Anisotropy and delayed relaxation of the anomalous Hall effect in GdFeCo/Ir/GdFeCo synthetic ferrimagnets

In synthetic ferrimagnets with perpendicular anisotropy GdFeCo/Ir/GdFeCo, the dependence of the hysteresis loops of the anomalous Hall resistance and the characteristics of the loops on the angle between the magnetic field and the plane of the sample are analyzed. The part of the anomalous Hall resistance corresponding to the spin-orbit torque has been identified. The field dependences of the resistance are sensitive to switching between the magnetic states of the two-layer ferrimagnet and they reproduce the shapes of the magnetization hysteresis loops, calculated with the interlayer exchange interaction, crystal anisotropy, and Zeeman energies at different angles between the field and sample. A slow (~30 min) magnetic relaxation of resistivity hysteresis after reorientation of the sample in magnetic field was found. Specific domain dynamics inherent in two-layer samples was revealed by Kerr microscopy. It was found that slow restoration of the resistivity hysteresis loop is due to domain propagation. Keywords: spin Hall effect, spin-orbit torque, magnetic relaxation, domain wall dynamics.

Manipulating the Micromagnetic Structure of Multiphase CoPt Thin Films by Varying Layer Thicknesses

The magnetic properties and micromagnetic structure of [Co/Pt]10 multilayer magnetic films formed by independent variation of the Co and Pt layer thicknesses have been studied. The possibility of the film magnetization parameters manipulation was shown. It is found that the micromagnetic structure of the layers is significantly modified with a change in the thickness of the layers which correlates with the magnetization data. In particular, magnetic force microscopy revealed a system of magnetic skyrmions for a number of structures. The skyrmion density was found to be dependent on the growth conditions which in turn correlates with the shape of the magnetic hysteresis loop. Changing the thickness of the Co and Pt layers makes it possible to control the density of skyrmions in the range from 0.2 to 10.5 mkm-2. Keywords: micromagnetic structure, skyrmions, CoPt films, electron beam evaporation.

Управление микромагнитной структурой многофазных тонких пленок CoPt путем варьирования толщин слоев

The magnetic properties and micromagnetic structure of [Co/Pt]10 multilayer magnetic films formed by independent variation of the Co and Pt layer thicknesses have been studied. The possibility of the film magnetization parameters manipulation was shown. It is found that the micromagnetic structure of the layers is significantly modified with a change in the thickness of the layers which correlates with the magnetization data. In particular, magnetic force microscopy revealed a system of magnetic skyrmions for a number of structures. The skyrmion density was found to be dependent on the growth conditions which in turn correlates with the shape of the magnetic hysteresis loop. Changing the thickness of the Co and Pt layers makes it possible to control the density of skyrmions in the range from 0.2 to 10.5 µm-2.

Анизотропия и медленная релаксация аномального эффекта Холла в синтетических ферримагнетиках GdFeCo/Ir/GdFeCo

In synthetic ferrimagnets with perpendicular anisotropy GdFeCo/Ir/GdFeCo, the dependence of the hysteresis loops of the anomalous Hall resistance and the characteristics of the loops on the angle between the magnetic field and the plane of the sample are analyzed. The part of the anomalous Hall resistance corresponding to the spin-orbit torque has been identified. The field dependences of the resistance are sensitive to switching between the magnetic states of the two-layer ferrimagnet and they reproduce the shapes of the magnetization hysteresis loops, calculated with the interlayer exchange interaction, crystal anisotropy, and Zeeman energies at different angles between the field and sample. A slow (~30 min) magnetic relaxation of resistivity hysteresis after reorientation of the sample in magnetic field was found. Specific domain dynamics inherent in two-layer samples was revealed by Kerr microscopy. It was found that slow restoration of the resistivity hysteresis loop is due to domain propagation.

Investigation of structural, dielectric characteristics of Nickel (Ni) doped Magnesium-Manganese (Mg-Mn) nano-ferrite

Spinel ferrites are extensively explored materials with wide application in the field of magnetic memory, magnetic resonance making, drug delivery agent and gas sensing devices. Nano scaled ferrites have technological important due to their excellent magnetic and electric properties executives enhanced saturation magnetization with rectangular shaped hysteresis loop, high dc. Resistivity, low dielectric loss, maximum curie temperature, superparamagnetic behavior, high initial permeability. These characteristics make Mg-Mn ferrites suitable for applications like switching circuit, hyperthermia and magnetic fluid. The essential condition for high frequency application is low-loss factor, low value of saturation magnetization, considerable permeability. Consequently, the present manuscript depicts synthesis and physicochemical characterizations of pristine and Ni2+ modified Mg0.9Mn0.1NixFe2-xO4 nanoparticles, where x = 0.0, 0.1,0.2. Physicochemical properties of all the compositions were carried using X-ray diffraction method, Scanning electron microscope (SEM) and LCR Impedance analyzer. Structural characterization revealed that pure synthesized of all the composition exhibiting face centered cubic crystallinity with space group Fd3¯m. Microstructural characterization showed irregular surface morphology with non-uniform grain distribution. The electrical characterization illustrated improvement in dielectric constant with Ni2+ doping in crystal lattice in Mg-Mn ferrites.

Site selective response of cationic dopants in ZnO nanomaterials: Optical, dielectric and magnetic behaviors

Modulations of dielectric response and the investigation of magnetic property due to the percentage variation (3, 5 and 7 wt%) of chromium ion doping in 5 wt% yttrium doped-ZnO nanomaterials are considered in this report. The rods like Cr3+ and Y3+co-doped ZnO nanomaterials with polycrystalline single phase of wurtzite lattice structure are prepared by hydrothermal synthesis route. Frequency and temperature dependent dielectric response of all the co-doped ZnO nanomaterials were investigated in this report and the observation suggests that the dielectric permittivity of these co-doped ZnO nanomaterials can be modulated based on the site selectivity of the cationic dopants like Cr3+ or Y3+in between the lattice sites and the interstitial sites inside the host ZnO lattice structure. In addition, low temperature (10 K) magnetic ordering with ‘S’ shape hysteresis loop are observed. The hysteresis curve has been fitted and contribution of each magnetic phase (paramagnetic and ferromagnetic) has been extracted. This report is not only helpful to understand the modulation of dielectric response of ZnO like semiconducting materials depending on site selectivity of the cationic dopants inside the lattice structure of ZnO but also explore the underlying physics of DMS system consisting of multiple magnetic phases. This study shows that the semiconductors based dielectric materials are more effective for tailor made applications in various dielectric devices.

Anomalous depinning of magnetic domain walls within the ferromagnetic phase of the Weyl semimetal Co3Sn2S2

We report bulk magnetization measurements and spatially resolved measurements of magnetic domains in single crystals. The results indicate that a previously reported magnetic anomaly around 130 K is due to an anomalous domain wall depinning upon cooling. Our measurements also reveal a hysteresis between field-cooled-cooling and field-cooled-warming magnetization curves acquired under a constant magnetic field below 300 Oe. This observation rules out the possibility that the anomaly stems from a second-order phase transition. Our results further suggest that changes in the shape of hysteresis loops from 5 to 170 K are caused by an unusual temperature-dependent domain nucleation field that changes sign around 130 K. The Kerr rotation images of the magnetic domains confirm that the domain walls depin between 120 and 140 K.

Phenomenological rate-independent uniaxial hysteretic models: A mini-review

A great variety of phenomenological models has been proposed over the years to model rate-independent hysteretic forces in structural mechanics. The classification of such models is usually based on the type of equation that needs to be solved to evaluate the output variable. In particular, we distinguish among algebraic, transcendental, differential and integral models. For algebraic (transcendental) models, an algebraic (a transcendental) equation needs to be solved to compute the output variable; conversely, differential equations are employed for differential models, whereas equations expressed in integral form characterize integral models. This paper provides a mini-review of the most adopted phenomenological rate-independent uniaxial hysteretic models. Such models are selected in order to provide a complete overview of the four types of previously mentioned models, currently available in the literature. In particular, we illustrate the fundamental characteristics of each model and discuss their peculiarities in terms of 1) number of adopted parameters and variables, 2) physical interpretation of parameters and related calibration procedures, 3) type of hysteresis loop shapes that can be simulated.

Enhanced energy-storage density of BaTi0.95Zr0.05O3 via generation of defect dipoles upon lithium-doping

Researchers seek the most optimal solutions to a worsening crisis and escalating energy demand. In light of this, ferroelectric (FE) ceramics have become increasingly important. In perovskite oxides, defect dipoles can significantly influence the dynamics of oxygen vacancies. The lithium ions were selected as acceptor ions doped Ba site of BaTi0.95Zr0.05O3 (BZT) based ceramics. A systematic investigation of its effect on the structural, dielectric, ferroelectric, and energy storage properties has been conducted. This study shows how to improve the energy storage density and efficiency by creating defect dipoles on the (BZT) host lattice. The obtained results indicate that Li-doping plays an essential role in changing the shape of hysteresis loops. Pinched hysteresis loops with high maximum polarization and small remnant polarization were acquired when the doping content was raised due to increasing the defect dipoles. Following the onset of defect dipoles induced by acceptor ions, the recoverable energy density increased from 0.191 J/cm3 to 0.701 J/cm3. In contrast, the energy storage efficiency increased 12th times compared to pure one, i.e., from 7% to 81%. The BLZT0.08 sample is also exceptionally stable over a range of temperatures and frequencies, making them a good candidate for applications in the field of energy storage. Improving energy storage density and efficiency by inducing defect dipoles in ferroelectric host-lattice may be one of the attractive approaches to developing ferroelectric materials for energy storage applications.