Narrow Results

This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PZT system. Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001–5Hz were performed by means of the electromechanical response characterization system (STEPHV) and program (STEP). It was found that the coercive field, remnant and saturation electric displacement, area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency. As a result of this study, complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.

In this paper, we study the magnetic properties of a tri-decorated $(\sigma =1/2,S=1,q=3/2)$ graphene structure using Monte Carlo simulations (MCS). Indeed, we first elaborate the ground state phase diagrams and then, we found that from $2\times 3\times 4=24$ phases, the only stable configurations are: $(\sigma ,S,q)=(-1/2,+1,-3/2)$, $(+1/2,-1,+3/2)$, $(-1/2,-1,-3/2)$, $(+1/2,+1,+3/2)$, $(-1/2,-1,+3/2)$, $(+1/2,+1,-3/2)$, $(-1/2,+1,+3/2)$, $(+1/2,-1,-3/2)$, $(+1/2,0,+3/2)$, $(-1/2,0,-3/2)$, $(+1/2,0,+1/2)$ and $(-1/2,0,-1/2)$. For low reduced temperature values, the partial magnetizations are found to be in good agreement with the corresponding ground state phase diagrams. The corresponding partial susceptibilities show a notable peak around the reduced temperature value 2.0 in the absence of the external magnetic field $(h/J_{\sigma S}=0.0)$ and crystal field $(\mathrm{\Delta }/J_{\sigma S}=0.0)$. To complete this study, we present and discuss the magnetic hysteresis loops.

The shifts in field-cooling hysteresis loops of antiferromagnetic nanoparticle systems have been widely observed in experiments. Here, numerical calculation is used to study the influence of the surface anisotropy and defects. It is found that surface defects alone are sufficient to yield the loop shifts (LS) at proper field angles. Neither the disordered nor the radial surface anisotropy is the indispensable ingredient to generate the LS. However, both of them play a role in enhancing the LS. The possible mechanisms are discussed.

This paper presents an investigation of the magnetic and magnetocaloric properties of a mixed Graphullerene-like nanostructure. The Blume–Capel model is employed, and Monte Carlo computations were performed using the Metropolis algorithm. The study examines various spin configurations within different parameter planes and reveals stable configurations. Furthermore, the paper analyzes magnetizations, susceptibilities, specific heat, and Binder cumulant as a function of the temperature to determine the transition temperature and characterize magnetic phase transitions in the system. The suitability of the investigated structure for magnetic refrigeration was also assessed by examining the magnetic entropy change and relative cooling power at different external magnetic field strengths. The results show a direct correlation between the external magnetic field and maximum entropy changes, indicating a significant magnetocaloric effect.

In this study, we performed extensive Monte Carlo simulations to comprehensively analyze the magnetic properties of a single-layer MXene-like lattice. Our investigation involved the exploration of transition temperatures and the behavior of hysteresis cycles, all influenced by a series of key physical parameters. Additionally, we carefully mapped the magnetization as a function of temperature and crystal field, introducing variations in the exchange coupling to unveil their impact on the transition temperature. Furthermore, we investigated the behavior of hysteresis loops, complexly dissecting their responses to changes in exchange coupling, temperature, and crystal field. Significantly, our results highlight the central role of the crystal field in the formation of magnetization plateaus, thus providing promising avenues for applications in nanotechnology and advanced memory storage systems.

The interaction of a mesoscopic system of coherently injected two-level Rydberg atoms with a coherently driven single cavity mode is treated outside the rotating wave approximation (RWA). The additional first harmonic component of the output field (outside RWA) exhibits closed hysteresis loops and multiple-switching processes, compared with the hysteresis cycles for the nonoscillatory (fundamental) component within the RWA. This is achieved via two controls: (i) varying the coherent population excitation and relative phase parameters (θ, ϕ) of the coherently injected atoms, and, (ii) varying simultaneously atom and cavity detuning parameters.

A two-dimensional computational model for infill walls is presented. The behavior of an infill wall is prescribed by a strength envelope and a hysteretic loop equation which provide smooth continuous curves. The infill is idealized with six compression-only inclined struts, which follow the behavior defined by the strength envelope and hysteretic loop equations. Three parallel struts are used in each direction, and the off-diagonal struts are located to represent the interaction between the infill and confining steel frame at locations along the beam-column spans where plastic hinges have been observed to form. The advantages of this analytical model are the following: (a) both strength and stiffness degradation of infill walls are modeled; (b) the parameters of the model have physical meaning and can be readily adapted to fit experimental data; (c) the off-diagonal struts allow modeling of the interaction between the infill and the bounding frame; and (d) local behavior, such as the effects of openings, lack of fit, and interface conditions, can be modeled.

In this paper, the fatigue hysteresis loops of fiber-reinforced ceramic–matrix composites (CMCs) under multiple loading stress levels considering interface wear have been investigated using micromechanics approach. Under fatigue loading, fiber/matrix interface shear stress decreases with the increase of cycle number due to interface wear. Upon increasing of fatigue peak stress, the interface debonded length would propagate along the fiber/matrix interface. The difference of interface shear stress existing in the new and original debonded region would affect interface debonding and interface frictional slipping between fibers and matrix. Based on the fatigue damage mechanism of fiber slipping relative to matrix in the interface debonded region upon unloading and subsequent reloading, the interface debonded length, unloading interface counter-slip length and reloading interface new-slip length are determined by fracture mechanics approach. The fatigue hysteresis loop models under multiple peak stress levels have been developed. The effects of fiber volume fraction, fatigue peak stress, matrix crack spacing, interface debonding and interface wear on interface slip and fatigue hysteresis loops have been analyzed.

The dielectric properties of a mixed Zethrene-inspired nanoscale system ($S_i^Z$-1, ${\sigma }_k^Z$-5/2) have been analyzed in detail using the Monte Carlo approach (MCa) in this study. First, the most stable configurations in different planes were investigated. Then, the influences of the physical factors, namely the coupling interaction factor, on the thermal behaviors of the polarization and the susceptibility of the studied nanostructure have been examined for nonzero temperatures and fixed external electric field values. It was found that the obtained transition temperature point relies weakly on the coupling interaction. Finally, the effects of the physical factors on the electric hysteresis cycles were discussed.

The Monte Carlo studies presented in this paper provide insight into stable phases, magnetic hysteresis cycles and magnetization plateaus in mixed nano-Kagome bilayer lattices. In particular, exchange coupling reduction affects coercive and saturation fields, and temperature variations impact hysteresis loop regions. The role of the crystal field in the design of magnetization plateaus was highlighted. The study explores the interaction of magnetization plates and their response to critical and saturation fields, depending on the crystal field and ferrielectric coupling. Extremely low temperatures ($T=0.01$) play a crucial role in the manifestation of magnetization plateaus. These results suggest possible applications in nanotechnology, particularly in the design of storage media.

Magnetic properties and hysteresis of a mixed spins (1, 2) hexagonal Ising nanowire with core–shell structure in the presence of lattice anisotropy and external magnetic field are investigated by using Monte Carlo simulation based on the Metropolis algorithm. First, we analyze the ground state phase diagrams to discover all probable and stable configurations based on minimizing the system energy. The effects of the exchange couplings ($J_{\mathrm{\text{int}}}$, $J_s)$ and the single-ion anisotropies ($D_c$, $D_s)$ on the magnetic quantities of the system, namely, the total magnetization, the transition temperatures and the hysteresis curves. Several characteristic behaviors are found, such as the appearance and the compensation behavior, which is of crucial importance for technological applications such as thermo-optical recording. Additionally, under certain physical parameters, multiple cycle hysteresis loops, such as single and triple hysteresis loops, that exhibit different step effects and various forms, are observed.