Influence Of Interparticle Interaction Research Articles

Evolution of an interacting fermion–antifermion pair in the near-horizon of the BTZ black hole

In this study, we investigate the evolution of a composite system comprising a fermion–antifermion pair engaged in Cornell-type non-minimal interaction in the near-horizon region of a BTZ black hole. Our exploration involves the derivation of an exact solution for the covariant two-body Dirac equation, derived from quantum electrodynamics through the action principle. To commence our analysis, we formulate the relevant equation, resulting in a 4×4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$4\ imes 4$$\\end{document} dimensional matrix equation that governs the relative motion of the fermion–antifermion pair. Notably, we demonstrate that this matrix equation results in an exactly solvable wave equation, enabling us to determine the relativistic frequency modes for this spinless static composite system. Our findings unveil a temporal decay in these modes, with the decay time explicitly dependent on both the inter-particle interaction and the spacetime parameters. Our comprehensive examination extends to a detailed analysis of the system’s evolution, shedding light on the influence of inter-particle interaction on the evolution of a fermion–antifermion pair in the near-horizon region of the BTZ black hole.

Influence of interparticle interaction on the structural, optical and magnetic properties of NiO nanoparticles

In this work, we have synthesized nickel oxide (NiO) nanoparticles using a simple wet chemical method. The synthesized nanoparticles were annealed at different temperatures ranging from 573 to 973 K. The structural, magnetic, and optical properties were characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM), Superconducting Quantum Interference Device (SQUID), UV–VIS and Photoluminescence (PL) spectrophotometer. The optical properties depict that as NiO particles grow bigger, the intensity of the UV emission increases. The broad emission band can be attributed to the direct recombination of photogenerated charge carriers from the conduction band with the holes in the valence band. This kind of emission due to the transition of 3d8 electrons of the Ni2+ ions was also observed in the PL spectra. NiO nanoparticles exhibit antiferromagnetic behaviour with varied magnetic moment values of 3.08–5.72 μB. The ZFC curves of all samples show cusp and sharp decrease in magnetization at temperatures in the region of 10–21 K. This is due to the surface cluster spins whose thermal fluctuations freeze in a cluster-glass-like state. The bifurcation temperature between ZFC-FC curves increases with respect to the particle size due to the exchange field which is related to the overlap of electron wave functions of two magnetic ions (Ni2+). This field acts indirectly through the neighbouring anions O2−, as Ni2+ ions are too far apart for direct exchange forces mechanism called super exchange and originates from Pauli exclusion principle and electrostatic force.

Oriented nanometric aggregates of partially inverted zinc ferrite: One-step processing and tunable high-frequency magnetic properties

In this work, it is demonstrated that the in situ growth of oriented nanometric aggregates of partially inverted zinc ferrite can potentially pave a way to alter and tune magnetocrystalline anisotropy that, in turn, dictates ferromagnetic resonance frequency (fFMR) by inducing strain due to aggregation. Furthermore, the influence of interparticle interaction on magnetic properties of the aggregates is investigated. Mono-dispersed zinc ferrite nanoparticles (<5 nm) with various degrees of aggregation were prepared through decomposition of metal-organic compounds of zinc (II) and iron (III) in an alcoholic solution under controlled microwave irradiation, below 200 °C. The nanocrystallites were found to possess high degree of inversion (>0.5). With increasing order of aggregation in the samples, saturation magnetization (at 5 K) is found to decrease from 38 emu/g to 24 emu/g, while coercivity is found to increase gradually by up to 100% (525 Oe to 1040 Oe). Anisotropy-mediated shift of fFMR has also been measured and discussed. In essence, the result exhibits an easy way to control the magnetic characteristics of nanocrystalline zinc ferrite, boosted with significant degree of inversion, at GHz frequencies.

Effect of surface modifier on flow properties of epoxy suspensions containing model plate-like nanoparticles

The influence of inter-particle interaction on the rheology of an uncured epoxy containing model α-zirconium phosphate (ZrP) nanoplatelets with aspect ratio of 160 is reported. Epoxy suspensions containing nanoplatelets exfoliated with tetra-n-butyl ammonium hydroxide (TBA), a low molecular weight quaternary ammonium cation, show short-range repulsive potential with weak elastic response at low concentration. At semi-dilute concentrations, the suspensions are solid-like at intermediate frequency and transition to viscous flow for time scales longer than the rotary diffusion process. The weak elasticity at intermediate frequency is attributed to the effect of Brownian motion on the rotational motion of the isolated plates. Suspensions containing nanoplatelets exfoliated with hydrophilic polyetheramine oligomers show similar behaviour to the ZrP-TBA system, but shifted to lower concentration. The rheological behaviour is attributed to steric stabilization of the nanoplatelets by extended oligomer brushes with short-range repulsive interactions. For suspensions containing nanoplatelets exfoliated with hydrophobic polyetheramines with shorter length, there is evidence for elastic response on local length scales and the flow behaviour shows strong history and temperature dependence. Rheological signatures associated with equilibrium nanoplatelet dispersions with repulsive interactions are discussed.

The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

The influence of interparticle interaction on the processes of magnetization reversal is considered for an ensemble of oriented Stoner–Wohlfarth nanoparticles. This is done through a solution of a kinetic equation describing the relaxation of the total magnetization to its equilibrium value in an effective mean field which includes a term proportional to the instantaneous value of the magnetization. It is shown that the interparticle interaction influences the temperature dependence of a coercive field. Under certain conditions, the presence of the interparticle interaction can lead to the formation of the so-called superferromagnetic state with the correlated directions of the magnetic moments of the particles. If the system is unable to come to the equilibrium during the time interval necessary to perform measurements, some measured quantities become dependent on the measurement time. It is shown that the blocking temperature Tb and the temperature dependence of coercive field at T<Tb are strongly dependent on a measurement time. At T>Tb, however, the coercivity, if exists, does not depend on the measurement time. The data of magnetostatic measurements, carried out on the (CoFeB)x–(SiO2)1−x nanogranular films with the concentration of ferromagnetic particles slightly lower than a percolation threshold, are in compliance with the results of the calculations.

Non-equilibrium dynamics in fine magnetic particle systems

Extended dynamics (broader than Debye relaxation) occurs in fine magnetic particle systems because of the particle size distribution and the influence of interparticle interaction. In dilute negligibly interacting systems the broadening of the relaxation is governed by the effective anisotropy distribution of the particles. In dense systems, however, interparticle interaction alters the nature of the dynamics and phenomena due to correlation of the particle moments appear. The effects may at a glance only look like a change in the effective anisotropy of the individual particles. However, studies of the dynamics over several decades in observation time reveal that correlation related effects dominate the dynamics on long time scales and extend the maximum relaxation time well beyond the relaxation time of the individual particles. In addition, non-equilibrium dynamics, reminiscent of the ageing phenomenon of spin glasses, appears. Results and analyses of ac susceptibility and magnetic relaxation experiments on various fine magnetic particle systems, ranging from concentrated monodispersed ferrofluids to mechanically alloyed granular materials, are used to illustrate the cooperative nature of the dynamics.

The influence of interparticle interaction on magnetization curves of nano-and microcrystal ensembles

Reconstruction of magnetization curves for real close-packed systems of highly anisotropic ferrimagnetic BaFe12O19 single-domain nano-and microcrystals is carried out on the basis of the results of a study of interparticle magnetic interaction. These curves allowed us to distinguish general laws of magnetization of ensembles of randomly oriented single-domain particles predicted by the Stoner-Wohlfarth theory and to discuss special features found for microcrystals.

Solution Properties of Glycogen. 2. Semidilute Solutions

Interparticle interaction and structure of glycogen from a shell fish (mussels) were studied in water and 0.5 N NaOH by static and dynamic light scattering and viscometry. A concentration regime up to 30% w/v was covered. Beyond the overlap concentration a large-scale clustering was observed which was interpreted as associates. Glycogen is a natural representative for hyperbranched polysaccharides. Interpretation of data was made for the inverse forward scattering (at scattering angle θ = 0). The measured quantities could be separated into interparticle interaction contributions and a change in the particle structure when the concentration was increased. A master curve was obtained for X < 1 when plotting Mw/Mapp(c) against X = A2Mwc = c/c*, where Mapp(c) is the apparent (measured) molar mass at concentration c. This master curve agrees within experimental error with that for amylopectin. Deviations to a flatter curve were found when X > 1. Simultaneously to the forward scattering the apparent radius of gyration Rapp(c) was measured. The influence of interparticle interaction could be split off, and the true Rg(c) was obtained. Up to X = 1 no change was observed, but at X > 1 a sharp increase in the dimensions by 2−3 orders in magnitude was found. Similar behavior was found also in dynamic light scattering where a slow mode of motion became noticeable at X > 2. These three effectsdeviation from the interaction master curve, increase in Rg(c), and development of a slow mode of motiongive strong evidence for onsetting association. The specific viscosity showed common behavior with a weak increase in the dilute regime and a strong increase in the semidilute regime. The kink points were found with c[η] = 0.57 and 0.82 for NaOH and H2O, respectively, much smaller than c[η] ≅ 4 as observed for most linear macromolecules. However, a very good agreement with latex particles was found.

Magnetic susceptibility of ferrocolloids with frozen texture

A theoretical analysis of the static and dynamic magnetic susceptibilities of a frozen moderately concentrated ferrocolloid is presented. The freezing of the fluid is assumed to take place in the presence of a constant external magnetic field. The steric and dipole-dipole interactions between ferroparticles are taken into account. We have studied the situations when current magnetic field is parallel and normal to the magnetic field applied during freezing. The influence of interparticle interaction on the real and imaginary parts of initial susceptibility is examined. The analysis of a stochastic resonance in this system is presented and the influence of interparticle interaction and field applied during freezing on signal-noise ratio is estimated.

Influence of packing density on recording media under high-speed field

We have studied the influence of interparticle interaction on the switching of recording media under a rapidly varying field. Two parallel particles with dipole-dipole coupling for arbitrary bond angle were treated analytically. Under a rapidly varying field, the oscillatory switching bands were observed before the static limit for small damping constant and bond angle. Interaction modifies the switching band shape but only the damping constant changes the band gap.