Symmetry and Its Application in Magnetism and Magnetic Materials

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 6062

Special Issue Editor

Department Spin and Topology in Quantum Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
Interests: experimental physics; solid state physics; magnetism; synchrotron radiation

Special Issue Information

Dear Colleagues,

Most of our surrounding physical world is guided by symmetry, which seems to be one of the omnipresent laws of the universe. Using symmetry, complex multidimensional systems can be easily explained and understood from both classical and quantum perspectives. Simplification relies on the fact that the system can be described by viewing one of its two identical aspects, even though the perspective views are different. On the other hand, theoretical local spontaneous symmetry breaking is responsible for the existence of crystals (breaking of transitional invariance) and magnetism (breaking of rotational invariance), as well as the superconductivity (where the phase of the charged particle is broken).

Properties of magnetic materials, bulk or thin films can be understood by taking into account their geometrical crystal symmetry (for crystalline structures) and/or their spin symmetry structure. Generally, one can include here ferromagnetic materials (e.g., 3d-transition metals and alloys), and antiferromagnetic materials (metallic alloys or oxides), as well as ferrimagnetic structures (3d-RE alloys, ferrites and garnets). Each of these types of magnetic materials exhibits an orderly distribution of their magnetic moments (spins) and the direction of this assumed spin can be seen as a repetitive feature on top of the geometrical description of the system (crystalline or amorphous).

Moreover, important aspects in magnetism and magnetic materials rely on distortion-affected symmetrical structures. Asymmetries of the ordered structures also lead to important aspects of some magnetic materials. Worth mentioning here is the antisymmetric part of the anisotropic (super)exchange interaction, later referred to as Dzyaloshinskii–Moriya interaction (DMI)—the fundamental interaction explaining the magnetic skyrmion structures or the magneto-electric effects in multiferroics.

The aim of this Special Issue is to pave the road for different possible experiments and publications having symmetry, magnetism and magnetic materials as common ground. Therefore, we encourage diverse contributions in a broad range of topics as follows:

  • Ferromagnetic and antiferromagnetic (ferrimagnetic) materials;
  • Skyrmions and other magnetic topological structures;
  • Spin structures and spintronics;
  • Symmetry breaking;
  • Models in magnetism;
  • Spin waves;
  • Exchange-coupled systems;
  • Low-dimensional systems;
  • Molecular magnets;
  • Multiferroics;
  • Dynamics in magnetism;
  • Magnetism in biological systems, etc.

Dr. Radu Abrudan
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • symmetry
  • magnetism
  • symmetry breaking
  • spintronics
  • topology
  • X-ray spectro-microscopy
  • X-ray and neutron scattering
  • thin films
  • single crystal

Published Papers (3 papers)

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Research

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24 pages, 6142 KiB  
Communication
Self-Organizing Equilibrium Patterns of Multiple Permanent Magnets Floating Freely under the Action of a Central Attractive Magnetic Force
by Iosif Vasile Nemoianu, Cristian George Dragomirescu, Veronica Manescu (Paltanea), Maria-Iuliana Dascalu, Gheorghe Paltanea and Radu Mircea Ciuceanu
Symmetry 2022, 14(4), 795; https://0-doi-org.brum.beds.ac.uk/10.3390/sym14040795 - 11 Apr 2022
Cited by 1 | Viewed by 1754
Abstract
The present communication revisits the almost century-and-a-half-old problem of some identical small magnets floating freely on the water’s surface under the action of a superimposing magnetic field created by a stronger magnet placed above them. Originally introduced and performed by Alfred Marshall Mayer [...] Read more.
The present communication revisits the almost century-and-a-half-old problem of some identical small magnets floating freely on the water’s surface under the action of a superimposing magnetic field created by a stronger magnet placed above them. Originally introduced and performed by Alfred Marshall Mayer and reported in a series of articles starting from 1878 onward, the proposed experiments were intended to provide a model (theoretical and educational) for the building block of matter that, at a microscopic level, is the atom. The self-organizing patterns formed by the repelling small magnets under the influence of a single attractive central force are presented in a slightly different reenactment of the original experiments. Although the set-up is characterized by an axially symmetric magnetostatic structure, and the floated magnets are all identical, the resulting equilibrium patterns are not necessarily symmetrical, as one would expect. To the authors’ best knowledge, the present communication proposes for the first time a quantitative approach to that extremely complex conceptual problem by providing a methodology for computing the equilibrium point coordinates in the case of n = 1…20 floating magnets, as proposed by the original A.M. Mayer experiments. A good agreement between the experiments and computed data was demonstrated for n = 2…15 (1st variant), but it was less accurate while still preserving the experimental set-up configurations for n = 15 (2nd variant)…20. Finally, this study draws the conclusions from the performed experiments and their corresponding computer simulations, identifies some open issues, and outlines possible solutions to address them, as well as future developments concerning the subject in general. Full article
(This article belongs to the Special Issue Symmetry and Its Application in Magnetism and Magnetic Materials)
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12 pages, 470 KiB  
Article
A New Formulation of Maxwell’s Equations
by Simona Fialová and František Pochylý
Symmetry 2021, 13(5), 868; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13050868 - 12 May 2021
Cited by 3 | Viewed by 2220
Abstract
In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In [...] Read more.
In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms. Full article
(This article belongs to the Special Issue Symmetry and Its Application in Magnetism and Magnetic Materials)
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Review

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16 pages, 7215 KiB  
Review
Constitutive Equations for Magnetic Active Liquids
by Simona Fialová and František Pochylý
Symmetry 2021, 13(10), 1910; https://0-doi-org.brum.beds.ac.uk/10.3390/sym13101910 - 11 Oct 2021
Cited by 1 | Viewed by 1102
Abstract
This article is focused on the derivation of constitutive equations for magnetic liquids. The results can be used for both ferromagnetic and magnetorheological fluids after the introduced simplifications. The formulation of constitutive equations is based on two approaches. The intuitive approach is based [...] Read more.
This article is focused on the derivation of constitutive equations for magnetic liquids. The results can be used for both ferromagnetic and magnetorheological fluids after the introduced simplifications. The formulation of constitutive equations is based on two approaches. The intuitive approach is based on experimental experience of non-Newtonian fluids, which exhibit a generally non-linear dependence of mechanical stress on shear rate; this is consistent with experimental experience with magnetic liquids. In these general equations, it is necessary to determine the viscosity of a liquid as a function of magnetic induction; however, these equations only apply to the symmetric stress tensor and can only be used for an incompressible fluid. As a result of this limitation, in the next part of the work, this approach is extended by the asymmetry of the stress tensor, depending on the angular velocity tensor. All constitutive equations are formulated in Cartesian coordinates in 3D space. The second approach to determining constitutive equations is more general: it takes the basis of non-equilibrium thermodynamics and is based on the physical approach, using the definition of density of the entropy production. The production of entropy is expressed by irreversible thermodynamic flows, which are caused by the effect of generalized thermodynamic forces after disturbance of the thermodynamic equilibrium. The dependence between fluxes and forces determines the constitutive equations between stress tensors, depending on the strain rate tensor and the magnetization vector, which depends on the intensity of the magnetic field. Their interdependencies are described in this article on the basis of the Curie principle and on the Onsager conditions of symmetry. Full article
(This article belongs to the Special Issue Symmetry and Its Application in Magnetism and Magnetic Materials)
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