D. Sander et al. “The 2017 Magnetism Roadmap” Journal of Physics D: Applied Physics, Volume 50, Number 36
Building upon the success and relevance of the 2014 Magnetism Roadmap, this 2017 Magnetism Roadmap edition follows a similar general layout, even if its focus is naturally shifted, and a different group of experts and, thus, viewpoints are being collected and presented. More importantly, key developments have changed the research landscape in very relevant ways, so that a novel view onto some of the most crucial developments is warranted, and thus, this 2017 Magnetism Roadmap article is a timely endeavour. The change in landscape is hereby not exclusively scientific, but also reflects the magnetism related industrial application portfolio. Specifically, Hard Disk Drive technology, which still dominates digital storage and will continue to do so for many years, if not decades, has now limited its footprint in the scientific and research community, whereas significantly growing interest in magnetism and magnetic materials in relation to energy applications is noticeable, and other technological fields are emerging as well. Also, more and more work is occurring in which complex topologies of magnetically ordered states are being explored, hereby aiming at a technological utilization of the very theoretical concepts that were recognised by the 2016 Nobel Prize in Physics.
Given this somewhat shifted scenario, it seemed appropriate to select topics for this Roadmap article that represent the three core pillars of magnetism, namely magnetic materials, magnetic phenomena and associated characterization techniques, as well as applications of magnetism. While many of the contributions in this Roadmap have clearly overlapping relevance in all three fields, their relative focus is mostly associated to one of the three pillars. In this way, the interconnecting roles of having suitable magnetic materials, understanding (and being able to characterize) the underlying physics of their behaviour and utilizing them for applications and devices is well illustrated, thus giving an accurate snapshot of the world of magnetism in 2017.
The article consists of 14 sections, each written by an expert in the field and addressing a specific subject on two pages. Evidently, the depth at which each contribution can describe the subject matter is limited and a full review of their statuses, advances, challenges and perspectives cannot be fully accomplished. Also, magnetism, as a vibrant research field, is too diverse, so that a number of areas will not be adequately represented here, leaving space for further Roadmap editions in the future. However, this 2017 Magnetism Roadmap article can provide a frame that will enable the reader to judge where each subject and magnetism research field stands overall today and which directions it might take in the foreseeable future.
The first material focused pillar of the 2017 Magnetism Roadmap contains five articles, which address the questions of atomic scale confinement, 2D, curved and topological magnetic materials, as well as materials exhibiting unconventional magnetic phase transitions. The second pillar also has five contributions, which are devoted to advances in magnetic characterization, magneto-optics and magneto-plasmonics, ultrafast magnetization dynamics and magnonic transport. The final and application focused pillar has four contributions, which present non-volatile memory technology, antiferromagnetic spintronics, as well as magnet technology for energy and bio-related applications. As a whole, the 2017 Magnetism Roadmap article, just as with its 2014 predecessor, is intended to act as a reference point and guideline for emerging research directions in modern magnetism.
R. Szewczyk “Generalization of magnetostatic method of moments for thin layers with regular rectangular grids” Acta Physica Polonica A 131 (2017) 845.
Possibilities of the modeling of the flux density distribution in thin films are significantly limited using the finite elements method due to the fast increase of the number of tetrahedral elementary cells with reduction of the thickness. For this reason, method of the moments is very important alternative for finite elements method in the case of thin layers, where layer’s thickness should be considered. Method of the moments overcomes this barrier, due to the possibility of operation on uniform grids with limited number of cells. Moreover, in opposite to the finite elements method, the method of the moments requires solving of the well defined linear equations, instead of the set of ill-posed differential equations. Paper presents the generalization of the method of the moments for thin layers with given thickness. Layers are defined as the 2D rectangular grids. Within the generalization, four key equations describing the influence of rectangular cell’s border on the magnetization of cells are stated. On the base of these dependences, the set of 2NM linear equations was determined, where N and M are the numbers of rectangular cells in the rows and columns of regular grid. Finally, the set of linear equations is solved and magnetic flux density distribution in the thin layer is calculated.