Structures, phase transitions, and magnetic properties of 
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 from first-principles calculations

“…From a theoretical point of view, determining the stability of a predicted phase is a hard task that requires an accurate calculation of the full phase diagram at finite temperature (free energy) [101,102]. In this section, inspired by isostructural tie-lines [103,104], we discuss about some general strategies to design experimental procedures for exploring most promising theoretical materials found in the Novamag database, fully based on their crystallographic data, by doping known stable phases.…”

Section: Synthesis and Characterization Of Hard Magnetic Phase Alloysmentioning

confidence: 99%

Database of novel magnetic materials for high-performance permanent magnet development

Nieves

Arapan

Maudes

et al. 2019

Computational Materials Science

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This paper describes the open Novamag database that has been developed for the design of novel Rare-Earth free/lean permanent magnets. The database software technologies, its friendly graphical user interface, advanced search tools and available data are explained in detail. Following the philosophy and standards of Materials Genome Initiative, it contains significant results of novel magnetic phases with high magnetocrystalline anisotropy obtained by three computational high-throughput screening approaches based on a crystal structure prediction method using an Adaptive Genetic Algorithm, tetragonally distortion of cubic phases and tuning known phases by doping. Additionally, it also includes theoretical and experimental data about fundamental magnetic material properties such as magnetic moments, magnetocrystalline anisotropy energy, exchange parameters, Curie temperature, domain wall width, exchange stiffness, coercivity and maximum energy product, that can be used in the study and design of new promising high-performance Rare-Earth free/lean permanent magnets. The results therein contained might provide some insights into the ongoing debate about the theoretical performance limits beyond Rare-Earth based magnets. Finally, some general strategies are discussed to design possible experimental routes for exploring most promising theoretical novel materials found in the database. NOVAMAG H c > M r /2 [5]. Extrinsic properties also depend on temperature, in fact they typically decrease as temperature increases, reducing the magnet's performance, especially close to the Curie temperature T C (i.e. ferromagnetic-paramagenetic transition). The macroscopic behavior is tightly linked to the microscopic properties called intrinsic. Main magnetic intrinsic properties are atomic magnetic moment µ at (the magnetic moment per volume gives the maximum theoretical M s ), exchange interactions J ij (which determine the magnetic order and T C )and magnetocrystalline anisotropy K 1 (that can enhance H c and it is indispensable in modern magnets to get H c > M r /2) [6]. PMs should have high atomic mangetic moments per volume (> 0.1µ B /Å 3 ), strong ferromangetic exchange interactions (able to give T C > 600 K) and high easy axis magnetocrystalline anisotropy (K 1 > 1 MJ/m 3 ) in order to exhibit good extrinsic properties suitable for PM applcations. In particular, magnetic materials with hardness parameter κ = K 1 /(µ 0 M 2 s ) > 1 (called "hard" magnets) are very valuable since can be used to make efficient magnets of any shape [6]. At mesoscopic scale, intergranular structure between the grains and crystallographic defects can strongly affect the performance of a magnet [7]. Therefore, the optimization of the material's microstructure is also very important in the design and devel-

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