Calculation and experimental verification of force-magnetic coupling model of magnetised rail based on density functional theory

Metal magnetic memory (MMM) is a widely used non-destructive electromagnetic detection technology. However, the analysis of its underlying principle is still insufficient. The mechanical and magnetic coupling model is a reasonable standpoint from which to study the principle of MMM. In this paper, a mechanical and magnetic coupling model of steel material is established based on density functional theory (DFT) using the CASTEP first-principles analysis software. In order to simulate the practical working environment, the residual magnetism in the rail is assumed to change with the stress on the rail. By applying different stresses to the model, the relationship between the atomic magnetic moment, the lattice constant and stress is explored, as well as the causes of magnetic signals in the stress concentration zone. It is revealed that the atomic magnetic moment and the crystal volume decrease with the increase in compressive stress. The magnetic signal on the surface of the magnetised metal component decreases with the increase in compressive stress, while the tensile stress shows the opposite tendency. Generally speaking, the change in atomic magnetic moment and crystal volume caused by lattice distortion under stress can be seen as the fundamental reason for the change in magnetic signal on the surface of the magnetised metal. The bending experiment of the rail shows that the normal magnetic field decreases with the increase in compressive stress in the stress concentration zone. The conclusion is verified by experiments.

Chemical Mesoscopics Notions in the Explanation of Polymeric Materials Modification Mechanism with Participation of Metal Carbon Mesocomposites

The paper is dedicated to the consideration of the chemical mesoscopics notions application for the explanation of polymeric materials modification mechanism by the metal carbon mesoscopic composites. The main peculiarities of these nanosized particles are following: a) the presence of unpaired electrons on the carbon cover; b) the structure of carbon cover consists from poly acetylene and carbine fragments; c) the atomic magnetic moment of inner metal is equaled to more than 1,3 μB. The creation of reactive mesoscopic materials with regulated magnetic characteristics which can find the application as modifiers of materials properties is very topical. The present investigation has fundamental character. It’s based on the ideas concerning to the metal carbon mesocomposites reactivity depending on the medium and conditions influence because of the possible changes of the phase coherency and quantization of negative charges.

Metal-carbon mesocomposites application possibilities as the medicine magnetic transport within an organism

The paper is dedicated to the consideration of the metal-carbon mesocomposites application possibilities for the medicine magnetic transport. This trend is determined by correspondent peculiarities of content and structure of mesoscopic composites. The main peculiarities of these nanosized particles are the following: a) the presence of unpaired electrons on the carbon shell; b) the structure of carbon shell from poly acetylene and carbine fragments; c) the atomic magnetic moment of inner metal is equaled to more than 1–3 μB. The creation of reactive mesoscopic materials with regulated magnetic characteristics which can find application as medicine magnetic transport within an organism is very topical. The present investigation has fundamental character. It’s based on the ideas concerning to the change of metal-carbon mesocomposites reactivity. The use is possible as metal-carbon mesocomposites both and they are modified analogously.

Structure, Magnetism, and Electronic Properties of Inverse Heusler Alloy Ti2CoAl/MgO(100) Herterojuction: The Role of Interfaces

In this study, the interface structures, atom-resolved magnetism, density of states, and spin polarization of 10 possible atomic terminations in the Ti2CoAl/MgO(100) heterojunction were comprehensively investigated using first-principle calculations. In the equilibrium interface structures, the length of the alloy–Mg bond was found to be much longer than that of the alloy–O bond because of the forceful repulsion interactions between the Heusler interface atoms and Mg atoms. The competition among d-electronic hybridization, d-electronic localization, and the moving effect of the interface metal atoms played an important role in the interface atomic magnetic moment. Unexpected interface states appeared in the half-metallic gap for all terminations. The “ideal” half-metallicity observed in the bulk had been destroyed. In TiAl–Mg and AlAl–O terminations, the maximal spin polarization of about 65% could be reserved. The tunnel magnetoresistance (TMR) value was deduced to be lower than 150% in the Ti2CoAl/MgO(100) heterojunction at low temperature.

Aspects of the Solid State

Symmetries play an important role in the theory of the solid state. As will be developed in this Chapter, DFT calculations for crystalline materials are commonly performed for the irreducible part of the first Brillouin zone, an approach which relies on the use of translational and point group symmetries. Two central properties that result from a calculation in reciprocal space are the wave vector resolved energy spectra, the so called band structure, and the energy resolved density of states. For magnetic materials, atomic magnetic moment moments can be defined and calculated, as well as effective inter-atomic exchange interactions.