Advances in nanostructured permanent magnets research

Abstract

This paper reviews recent developments in research in nanostructured permanent magnets (hard magnetic materials) with emphasis on bottom-up approaches to fabrication of hard/soft nanocomposite bulk magnets. Theoretical and experimental findings on the effects of soft phase and interface conditions on interphase exchange interactions are given. Synthesis techniques for hard magnetic nanoparticles, including chemical solution methods, surfactant-assisted ball milling and other physical deposition methods are reviewed. Processing and magnetic properties of warm compacted and plastically deformed bulk magnets with nanocrystalline morphology are discussed. Prospects of producing bulk anisotropic hard/soft nanocomposite magnets are presented.

Symmetry-lowering lattice distortion at the spin reorientation in MnBi single crystals

“…Due to its high Curie temperature and strong magnetic anisotropy, MnBi has attracted increasing attention in the pursuit of rare-earth-free permanent magnets (see for example the review by Poudyal and Liu [1]). Advances in the understanding of the properties and processing of this material continue, despite its relatively simple, NiAs-type crystal structure, and the fact that ferromagnetism in MnBi was first reported over a century ago [2].…”

Magnetism and electron transport of MnyGa (1 < y < 2) nanostructures

“…3 Some of the rare-earth elements used in strong permanent magnets are critical materials and there are serious concerns over the price and supply of these materials. 4 Therefore, there have been intense research efforts in identifying and developing novel rare-earth free high-anisotropy magnets. Some of the non-rare-earth-element-based permanent magnet materials of current interest are the manganese-based ferromagnetic materials including MnBi, 5,6 MnAl, 7 and MnGa.…”

Simulation of alnico coercivity

“…Interestingly, some of the above features are also encountered in fine-particle and nanowire magnetism [ 22,24,[38][39][40][41][42]. For example, fine particles also exhibit a transition from coherent rotation to curling, and wireend features affect the coercivity [24,25,43].…”