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We studied some magnetic behaviors of the Ising model in a triangular spin tube using the effective field theory (EFT) with correlations. We examined the effects of the exchange anisotropy $$J^{\prime} = \frac{{J_{ \bot } }}{{J_{//} }}$$ , and temperature T on the magnetic properties of the spin ½ Ising model in a triangular spin tube, particularly for isotherm magnetization, spontaneous magnetization, and magnetic susceptibility. We investigated the magnetic properties of the triangular spin ½ tube in detail. At low temperature, magnetization curves of a triangular spin ½ tube of the Ising model with the intra- triangular J┴, and inter-triangular J// interaction exchange are examined within the behavior magnetic. It is shown that the developed model satisfactorily describes all pronounced features of the low-temperature magnetization process and the magneto-thermodynamics such as abrupt changes of the isothermal magnetization curves, a giant magnetocaloric effect. Among the most notable features of zero-temperature magnetization curves, one could mention fractional magnetization plateaus, quantum spin liquids, and macroscopic magnetization jumps, which can be found first of all in frustrated quantum Heisenberg spin models.

In this work, we studied the magnetic properties of a regularly tetrahedral molecule made of four spin-½, interconnected by exchange. For this purpose, we used the Heisenberg model and performed an exact resolution. In the case of a ferromagnetic coupling among the spins, the system orders itself under a magnetic field without displaying any net spontaneous magnetization. It behaves as a high spin-2 unique magnet. Under antiferromagnetic exchange, some exotic behaviour has been revealed due to the frustration governing the spin edifice. Thus, the magnetization is quantized into plateaus, which are separated by quantum phase transitions. In particular, we have argued the possibility of a quantum spin liquid (QSL) state that can occur at low temperature. This contribution intends mainly to bring single-molecular magnets to the front line of innovative nanoscale applications.

In this paper, we study the magnetic properties of a molecule composed of two inverted spin-½ tetrahedra sharing their common vertex via a spin-1. We achieve an exact resolution using the Heisenberg model. As long as the exchange couplings are predominantly ferromagnetic, the spin structure is fully saturated and behaves like a large spin-4 unique magnet. Antiferromagnetic coupling can strongly frustrate the spins of the nanodevice. This may lead to several exotic phenomena. Therefore, the magnetization can be quantified into plateaus separated by quantum phase transitions. The work is intended to inspire researchers to develop molecular magnets as a basis for innovative nanoscale engineering applications.

The hysteresis loops and compensation behaviors of a ferrimagnetic mixed system, consisting of two sublattices (A and B) with different spins (SA = 1 and SB = ½) and described by Heisenberg Hamiltonian on a cubic lattice, are investigated by using the pair approximation method. We have discussed the dependence of the compensation temperature on the D- crystal field interaction and J-exchange anisotropy. The influence of the longitudinal magnetic field and the magnetic hysteresis loops are also carried out. It is found that the model of mixed spin exhibits the possibility of two compensation points for several given sets of parameters. The model yields also second-order and first-order phase transitions, in addition to tricritical points. The reentrant phenomena can occur in some narrow ranges of D /|Jz| and Jxy /|Jz |. We have also observed the existence of triple hysteresis loop behaviors under the effects of special intrinsic parameters.

Background Non-alcoholic fatty liver disease (NAFLD) is a public health problem lacking an approved pharmacological treatment. Omega-3 fatty acids have shown to reverse NAFLD. Chia is a seed rich in α-linolenic acid (ALA), antioxidants, and fiber; therefore, it could be useful to treat NAFLD. Methods In a single arm experimental design study, the effect of 25 g/day of milled chia was assessed in 25 patients with NAFLD. After two weeks of dietary stabilization (basal condition) and eight weeks of a chia-supplemented isocaloric diet, liver:spleen attenuation index and visceral abdominal fat (VAF) were measured by computed tomography. Lipids, lipoproteins, free fatty acids (FFA), and ALA plasma concentrations were also determined. Results Dietary chia supplementation induced an increase in plasma ALA concentration (75%) and dietary fiber (55%) consumption. After chia supplementation, VAF (9%), body weight (1.4%), total cholesterol (2.5%), non-high density lipoprotein cholesterol (3.2%), and circulating FFA (8%) decreased. Furthermore, NAFLD regressed in 52% of the treated patients (P Conclusions The results of the present study show that 25 g/day of milled chia ameliorates NAFLD. Chia is an accessible vegetal source of omega-3 fatty acids, antioxidants, and fiber, which could have the potential to prevent metabolic abnormalities in NAFLD patients. Considering that there is no pharmacological treatment approved for NAFLD, the findings of the present study suggest that a chia-supplemented diet could be an innovative alternative to control this disease. Retrospectively registered https://clinicaltrials.gov/show/NCT03942822

We explore the adsorption properties of Fe-Phthalocyanine (FePc) molecule at various configurations of silica films supported by Ru(0001) and report on the geometric, electronic and magnetic features of the energetically preferred structures to fully understand the influence of the silica films on the adsorption properties of the FePc molecule. The investigation is carried out with the use of density of functional theory calculations and the self-consistent inclusion of van der Waals interaction. In addition, Oxygen atoms are added to govern the atomic structure of the silica overlayers on the surface. Our results show that both FePc/silica thin film systems exhibit both physisorption and chemisorption simultaneously. In addition, the FePc molecule on each substrate undergoes a symmetry reduction driven by mismatch with the substrates' symmetry as well as the breakup of the degenerate orbitals of Fe.

In this work, the effect of thermal fluctuation field on the magnetization dynamics in Co1.5Fe1.5Ge alloy free layer is reviewed in a spin-valve structure with in-plane magnetization using the stochastic Landau-Lifshitz-Gilbert-Slonczewski (s-LLGS) equation taking into account the thermally assisted switching. The ultimate goal is to systematically study the heating effect on the magnetization reversal by simulating the magnetization dynamics in different thicknesses under very low current densities of about 106–105 A/cm2 in the presence of the thermal effect by applying different temperature values between T = 50 and T = 200 K. Results showed that the magnetization has different reversal processes among the large and small temperature values due to the competition between the thermal energy Et and magnetic energy barrier Eb, which allows the magnetization to trigger switching for specific temperature values. Consequently, at a temperature increase of about 200 K, we have proved that the magnetization reversal in Co1.5Fe1.5Ge alloy free layer is possible under a low current density of J =− 3.5 × 106 A/cm2. Additionally, we carefully examined the thermal impact on the threshold current density and switching time through analyzing the magnetization behavior for each temperature value, and as a result, we succeeded to reduce the critical current density in Co1.5Fe1.5Ge/Ag/Co1.5Fe1.5Ge structure from Jc = − 5.7 × 106 A/cm2 to Jc = − 9.5 × 105 A/cm2 for a thickness of 1 nm.

There has been a significant increase in research of magnetocaloric materials because of its efficiency and environment friendliness for magnetic refrigeration applications at room temperature. The investigation of magnetocaloric effect (MCE) in RE5(SixGe1−x)4 alloys (where RE = Gd) shows large entropy changes ∆Sm over a wide range of temperature. In this work, we study the GMCE in Gd5Si2Ge2 alloy using Monte Carlo simulation. To attain this aim, we use DFT first to determine the exchange couplings of the alloy. The studied compound displays a magnetic entropy change of −∆Sm = 9.97 J/kg.K when subjected to a change of 0–5 T in the magnetic field, and also undergoes structural modifications whose effects recur on the magnetic behavior. In addition, this work is comforted by the agreement with previous experimental results.

Skyrmions are considered as topologically protected magnetic textures; they are covering a large area of applications. In this work, we studied using micromagnetic simulations the emergence of skyrmions in a nanodisk stacked in a FM/NM/FM multilayer system. We show how the skyrmion is formed through the antiferromagnetic interlayer exchange coupling (IEC). We also show the impact of the IEC on skyrmion size in both layers. We try as a conclusion to identify the range of IEC where skyrmions could exist in such systems.

In this paper, we study the magnetization behavior in Co40Fe40B20 nanodisks with Dzyaloshinskii-Moriya interaction, which is induced by a Pt layer. The known giant perpendicular magnetic anisotropy (PMA) in thin films elaborated from this kind of materials improves the topological structures nucleation. Our work consists in investigating the skyrmions apparition and stability in amorphous CoFeB nanodisks. The detected skyrmions are not spontaneously nucleated. Their nucleation is induced by an applied external field. We also study reversal magnetization of CoFeB and we elucidate skyrmions nucleation and annihilation.

An effective field method has been employed to study the magnetic properties of a ferrimagnetic mixed-spin Ising trilayer nanographene structure. The system is formed by alternate layers of two different spins atoms A (spin-1) and B (spin-½) arranged in a particular fashion A–B–A for which the nearest-neighbor spins of each layer are coupled ferromagnetically (JA and JB), whereas the cross atom interaction A-B (interlayer) is antiferromagnetic (JAB). We examined the effects of interlayer (or intra-layer) exchange coupling and single-ion anisotropy on the magnetization curves of the system. We found that the antiferromagnetic inter-layers (JAB

In this paper, a calculation model is proposed to measure magnetocaloric effect (MCE) and relative cooling power (RCP) in composites based on magnetic materials underscoring a giant MCE at room temperature. The two composite materials targeted are Gd-Gd5Si2Ge2 and MnAs- Mn 1 + δ As 0.9 Sb 0.1 due to their high magnetic entropy change ΔSM over 270–300 K and 280–320 K. Our selected composites could give a larger RCP value among existing magnetocaloric materials for magnetic refrigeration in the temperature range of 280–300 K which is desirable for ideal Ericsson-cycle magnetic refrigeration. The excellent magnetocaloric properties of these two magnetic composites make them attractive for active magnetic refrigeration at room temperature.

Nanometric spin structures such as skyrmions are covering a large area of applications related to new technologies. In this paper, we carry out a computational study on magnetic skyrmions behavior in Pt/CoFeB/Ru/CoFeB antiferromagnetic-exchange coupled systems. We aim to explore the possibilities of skyrmions nucleation in such multilayer. We demonstrated that skyrmions could be hosted in such system under specific conditions. We also studied the in-plane and out-of-plane reversal magnetization processes for these magnetic multilayers in order to check the skyrmion behavior under magnetic field loops.

In this paper, we investigate the magnetic behavior of a single-walled hexagonal spin-1 Ising nanotube by using the effective field theory (EFT) with correlations and the differential operator technique (DOT). The system consists of six long legs distributed parallel to each other on a hexagonal basis. Within each chain, spin sites are regularly positioned and magnetically coupled through a J// exchange interaction along the chains and J⊥ between adjacent chains. Key equations of magnetization, susceptibility and critical temperatures are established, numerically resolved and carefully analyzed for some selected exchange couplings and various applied magnetic fields. In addition to the phase diagram, interesting phenomena are noted, particularly for opposite exchange interactions where magnetization plateaus and frustration are discovered.

The effective field theory with correlations has been employed to study the hysteresis behavior of a ferromagnetic and ferrimagnetic three-walled mixed-spin Ising nanotube with an inner hexagonal vacancy. The effects of different exchange couplings, single-ion anisotropies, and temperature on the hysteresis loops of the sublattices and the overall system are attentively discussed. Multiple hysteresis loops have been observed in the system under certain physical hamiltonian parameters. It is found that the remanences and the coercivity of the sublattices and the system are strongly affected by the temperature, the exchange couplings, and the anisotropy. A satisfactory agreement can be qualitatively achieved by comparing our results with experiments and theoretical studies. Amazing behaviors are revealed thanks to the geometry, the different spins, and the multiple interactions involved in the system.

In this work, the magnetization states under the spin-transfer switching effect are investigated in a nanopillar device composed of a half-metallic Heusler Co 1.5 F e 1.5 G e alloy with a four-fold in-plane magnetocrystalline anisotropy. A comparative study with a half-metallic Heusler alloy of Co 2 F e A l 0.5 S i 0.5 and a typical material of Fe is realized by numerically solving the Landau-Lifshitz-Gilbert (LLG) equation with the Spin-Transfer Torque (STT) contribution, using micromagnetic simulations. Our ultimate goal is to elucidate the origins of the intermediate state (IS) that occurs during magnetization switching by deeply examining the effects of magnetocrystalline anisotropy and shape anisotropy on the magnetization states through analyzing and comparing various switching processes. Our simulation results showed that the magnetization switching via a single-step under low current densities is possible at certain critical cross-sectional dimensions of the ellipse that are adjusted to increase the demagnetization field against the four-fold in-plane magnetocrystalline anisotropy. As well, we provided in this paper a set of appropriate geometric dimensions which allow the magnetization to reverse via a single-step by overcoming IS with minimal spin-polarized current densities.

The magnetization loops of a hexagonal spin-3/2 Ising nanotube are examined in the framework of the effective field theory with correlations, based on the differential operator technique. We have explored the impacts of distinctive exchange couplings on key physical parameters such as Phase diagram, magnetization, susceptibility, internal energy, and specific heat. Some special phenomena are inspected in terms of thermal effects or crystal-field when the other inherent parameters of the nanotube are adjusted. Furthermore, We have found that the exchange couplings, the temperature, and single-ion anisotropy have a strong impact on the shape and the number of hysteresis loops as well as on the coercive field and magnetization behaviors.

The magnetic behavior of the spin - ½ Ising system, consisting of a squared four-legs Nanotube connected to each other by different exchange couplings, have been studied by mean of the effective field theory (EFT). The Nano-system can be immersed in an applied homogenous magnetic field. In addition to the transversal J⊥ and longitudinal J//interactions, we attentively examine the influence of the diagonal exchange interaction Jd on the main thermodynamic variables such as internal energy, spontaneous magnetization, isothermal magnetization, and initial susceptibility. The results show that critical temperature is enhanced with increasing the diagonal exchange coupling strength, while the isothermal magnetization curves can display jumps and plateaus at special values of the applied field, especially at lower temperatures. Our study proves also that the sign and the strength of each exchange coupling constant play a key role in the global magnetic behavior of this single-wall squared Nanotube spin. In particular, antiferromagnetic diagonal exchange interaction can lead to strong frustration.

Skyrmions are viewed as the basic elements for the future generation of magnetic memories. Their small sizes and good dynamical properties give them the ability to store and transport information easily. In this paper, we used micromagnetic simulation to study the contribution of interlayer exchange coupling and the geometrical confinement on scaling magnetic skyrmions. We started the work by comparing the utility of interlayer exchange coupling to the perpendicular magnetic field in scaling magnetic skyrmions. Then, we investigated the effect of combining the interlayer exchange coupling and geometrical confinement to reduce skyrmions size.

Magnetic skyrmions have attracted a great deal of interest in the last decades. They are widely used for many spintronic applications. In this manuscript, we study by micromagnetic simulation the emergence of a hexagonal Neel-type skyrmion lattice in a square thin film of CeFeB. We specifically examine the formation and annihilation of the skyrmion lattice. Moreover, we show the decrease of the skyrmion sizes with the increase of the magnetic field, while the lattice parameter remains unchanged during this rise.

We investigated the magnetization switching by means of a spin-polarized current via spin-transfer torque (STT) in a half-metallic Heusler Co1.5Fe1.5Ge alloy by numerically solving the Landau–Lifshitz–Gilbert–Slonczewski equation including the STT term in a spin-valve nanopillar Co1.5Fe1.5Ge/Ag/Co1.5Fe1.5Ge using micromagnetic simulation. In this work, we use Co1.5Fe1.5Ge film of 2 nm thickness, and then we inject a spin polarization current perpendicular to plane of the multilayers in order to flip the free layer magnetization and therefore get the magnetization switching between the two layers. Half-metallic Heusler Co1.5Fe1.5Ge is characterized by a small Gilbert damping constant α = 0.0025 and a complete spin polarization at the Fermi level. Using these specific parameters, we obtain the magnetization switching between the free layer and the pinned layer with a critical current density of about 106 A/cm2, as well the magnetization switching process of nanopillar are discussed and analyzed. Also, we deeply examine the behavior of magnetization switching dynamic as a function of the current density within a weak external magnetic field which helps to trig switching. Finally, we studied the impact of free layer thickness on magnetization switching dynamic and STT energy in order to immunize further the switching time and the critical current density.

We use the Pair Approximation method to analyze the magnetic and magnetocaloric behaviors of diluted mixed spin SA = 1 and spin SB = 1/2 with the anisotropic Heisenberg model, on a cubic lattice with coordination number z=6. Our system is described in presence of an external magnetic field; the phase diagram and thermodynamic properties related to the concentration of magnetic atom (A or B) and the single ion anisotropy are constructed and discussed. Special attention is paid to magnetocaloric properties provided by isothermal entropy change as well as the cooling capacity. These cooling power keys are plotted and discussed as a function of interaction anisotropy and magnetic component concentration of two sublattices ions A and B. Numerical results show a double peak structure in the entropy change curve and the inverse magnetocaloric effect related to the presence of the negative single-ion anisotropy.

Entamoeba histolytica virulence has been attributed to several amoebic molecules such as adhesins, amoebapores and cysteine proteinases, but supporting evidence is either partial or indirect. In this work we compared several in vitro and in vivo features of both virulent E. histolytica (vEh) and non-virulent E. histolytica (nvEh) axenic HM-1 IMSS strains, such as complement resistance, proteinase activity, haemolytic, phagocytic and cytotoxic capacities, survival in mice caecum, and susceptibility to O2. The only difference observed was a higher in vitro susceptibility of nvEh to O2. The molecular mechanism of that difference was analyzed in both groups of amoebae after high O2 exposure. vEh O2 resistance correlated with: (i) higher O2 reduction ( O 2 - and H2O2 production); (ii) increased H2O2 resistance and thiol peroxidase activity, and (iii) reversible pyruvate: ferredoxin oxidoreductase (PFOR) inhibition. Despite the high level of carbonylated proteins in nvEh after O2 exposure, membrane oxidation by reactive oxygen species was not observed. These results suggest that the virulent phenotype of E. histolytica is related to the greater ability to reduce O2 and H2O2 as well as PFOR reactivation, whereas nvEh undergoes irreversible PFOR inhibition resulting in metabolic failure and amoebic death.

Technologies based on magnetic skyrmions, such as computational devices that can operate at high speed or with low energy consumption, have been proposed by many researchers. Recently, synthetic antiferromagnetic (SAF) structures have been proposed to increase the stability and mobility of skyrmions by reducing or eliminating the skyrmion Hall effect. Here, we numerically study the current-induced dynamics of skyrmions on SAF bilayer structures. We demonstrate the effective control and manipulation of SAF skyrmions, including directional displacement and alignment. Furthermore, we design SAF-skyrmion-based logic gates, such as the and, or, xor, and not gates. Our design provides guidance for future development of spintronic computing devices that use topological nanoscale spin textures as information carriers.