Nonmagnetic impurities and roughness effects on the finite temperature magnetic properties of core–shell spherical nanoparticles with antiferromagnetic interface coupling

Abstract

Being inspired by a recent study [V. Dimitriadis et al. Phys. Rev. B 92, 064420 (2015)], we study the finite temperature magnetic properties of the spherical nanoparticles with core-shell structure including quenched (i) surface and (ii) interface nonmagnetic impurities (static holes) as well as (iii) roughened interface effects. The particle core is composed of ferromagnetic spins, and it is surrounded by a ferromagnetic shell. By means of Monte Carlo simulation based on an improved Metropolis algorithm, we implement the nanoparticles using classical Heisenberg Hamiltonians. Particular attention has also been devoted to elucidate the effects of the particle size on the thermal and magnetic phase transition features of these systems. For nanoparticles with imperfect surface layers, it is found that bigger particles exhibit lower compensation point which decreases gradually with increasing amount of vacancies, and vanishes at a critical value. In view of nanoparticles with diluted interface, our Monte Carlo simulation results suggest that there exists a region in the disorder spectrum where compensation temperature linearly decreases with decreasing dilution parameter. For nanoparticles with roughened interface, it is observed that the degree of roughness does not play any significant role on the variation of both the compensation point and critical temperature. However, the low temperature saturation magnetizations of the core and shell interface regions sensitively depend on the roughness parameter.

Surface Roughness Effects on Magnetic Properties and Switching Mechanism in Iron Nanowires

“…The existing theoretical simulations of surface roughness and its influence on the magnetic properties of material are commonly based on the micromagnetic approach [13][14][15]21,24]. However, discretization of the material's space into cuboidal cells (with the typical size of a few nanometres) may not always accurately capture the microstructure of the material.…”

Magnetics Properties Observed via a Contour From Xyz Data and Z Value as Label for Each Xy Data Point

“…The ratio surface/volume is the consequence of several physical properties and phenomenon [15].Some numerous experimental techniques have been reported to get nanoscales magnetic materials [16][17][18][19] and theoretically, the magnetic properties of these nanoparticles have mainly been examined by using the mean-field theory (MFA), the effective-field theory (EFT), and the Monte Carlo simulation (MC) [20][21][22][23][24][25][26][27][28][29] with a constant exchange interaction [30,15,22,26]. Otherwise, some investigations have been realized by using a random exchange interaction [31,32,33]. The aim in this paper is to present a way for displaying the ferromagnetic properties (magnetizations) from a contour with XYZ data and Z value as label for each XY data pointby using an EFT within the probability distribution technique and a random exchange interaction.…”

New Magnetics Observations with a Random Exchange Interaction

“…Because of this process, these nanoparticles start to exhibit new phenomenon and interesting physical properties which are totally different from those observed in the bulk materials [15]. Some numerous experimental techniques have been reported to get nanoscales magnetic materials [16][17][18][19] and theoretically, the magnetic properties of these nanoparticles have mainly been examined by using the mean-field theory (MFA), the effective-field theory (EFT), and the Monte Carlo simulation (MC) [20][21][22][23][24][25][26][27][28][29]. Otherwise, the exchange interaction is among the most important parameters in the magnetic properties, several authors have already worked on it with different forms [30,15,22,26], moreover, almost all the scientific investigations in the magnetic field are done with a constant exchange interaction.…”