Magnetic and magnetocaloric properties of the Co2-xMn B system by experiment and density functional theory

Ener, Semih; Fries, Maximilian; Hammerath, Franziska; Opahle, Ingo; Simon, Eszter; Fritsch, Patrizia; Wurmehl, S.; Zhang, Hongbin; Gutfleisch, Oliver

doi:10.1016/j.actamat.2018.11.034

Cited by 11 publications

(7 citation statements)

References 41 publications

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“…While GGA typically yields lattice parameters in better agreement with experiment, the local spin magnetic moments are often better described within LSDA. As the MAE depends on subtle details of the electronic structure, this can have a strong impact on the calculated MAE [77], as is the case here for Mn 3 Ir, Mn 3 PtN and Mn 3 SbN. According to the table, Mn 3 XN and Mn 3 X (X=Rh, Ir, Pt and Sb) would have a huge potential for application as hard magnets, provided they could be stabilized in a ferrimagnetic magnetic structure.…”

Section: Stable Interstitial Phasesmentioning

confidence: 71%

Effect of N, C and B interstitials on the structural and magnetic properties of alloys with Cu$_3$Au-structure

Opahle,

Singh,

Zemen

et al. 2020

Preprint

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High-throughput density functional calculations are used to investigate the effect of interstitial B, C and N atoms on 21 alloys reported to crystallize in the cubic Cu3Au structure. It is shown that the interstitials can have a significant impact on the magneto-crystalline anisotropy energy (MAE), the thermodynamic stability and the magnetic ground state structure, making these alloys interesting for hard magnetic, magnetocaloric and other applications. For 29 alloy/interstitial combinations the formation of stable alloys with interstitial concentrations above 5% is expected. In Ni3Mn interstitial N induces a tetragonal distortion with substantial uniaxial MAE for realistic N concentrations. Mn3XNx (X=Rh, Ir, Pt and Sb) are identified as alloys with strong magneto-crystalline anisotropy. For Mn3Ir we find a strong enhancement of the MAE upon N alloying in the most stable collinear ferrimagnetic state as well as in the non-collinear magnetic ground state. Mn3Ir and Mn3IrN show also interesting topological transport properties. The effect of N concentration and strain on the magnetic properties are discussed. Further, the huge impact of N on the MAE of Mn3Ir and a possible impact of interstitial N on amorphous Mn3Ir, a material that is indispensable in today's data storage devices, are discussed at hand of the electronic structure. For Mn3Sb, non-collinear, ferrimagnetic and ferromagnetic states are very close in energy, making this material potentially interesting for magnetocaloric applications. For the investigated Mn alloys and competing phases, the determination of the magnetic ground state is essential for a reliable prediction of the phase stability. FIG. 2. Interstitial positions in the Cu3Au-structure: 1b, 3d and 8g (from left to right).

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Section: Stable Interstitial Phasesmentioning

confidence: 71%

Effect of N, C and B interstitials on the structural and magnetic properties of alloys with Cu$_3$Au-structure

Opahle,

Singh,

Zemen

et al. 2020

Preprint

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“…In several cases, the results on (Fe 1−x Co x ) 2 B alloys were the effect of synergy between experiment and theory [11,12,15]. Finally, also a number of related boride phases, such as Co 2−x Mn x B, (Fe x Co 1−x ) 3 B, and Mn 0.95−δ Fe 1.05−δ−x Co x B [21][22][23], have been studied recently to tune their magnetic properties. In this work, we investigate the rare-earth-free magnet (Fe 0.7 Co 0.3 ) 2 B and alloys substituted with Re and W. The Co content and the type of dopant elements were predicted in a previous study [11] in which one of us participated.…”

Section: Introductionmentioning

confidence: 93%

Structural transformation and magnetic properties of (Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with 5$d$ elements: A combined first-principles and experimental study

Musiał¹,

Marciniak²,

Z.³

et al. 2021

Preprint

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Fe,Co) 2 B-based compounds with specified 5d substitutions are considered as promising materials for permanent magnets without rare-earth elements. We conducted a combined first-principles and experimental study focused on (Fe 0.7 Co 0.3 ) 2 B alloys doped with W and Re. First, we used fullpotential local-orbital scheme to systematically investigate (Fe,Co) 2 B alloys with 3d, 4d, and 5d substitutions. Computational analyses showed a significant increase in magnetocrystalline anisotropy only for the Re doped sample. Simultaneously, the structural and magnetic properties of the (Fe 0.7−x Co 0.3−x M 2x ) 2 B (M = W, Re; x = 0, 0.025) alloys were investigated experimentally. The desired (Fe,Co) 2 B tetragonal phase was synthesized by heat treatment of amorphous precursors. We observed that isothermal annealing increases the coercive field of all samples. However, the obtained values, without further optimization, are well below the threshold for permanent magnet applications. Nevertheless, annealing of substituted samples at 750 o C significantly improves saturation magnetization values. Furthermore, Mössbauer spectroscopy revealed a reduction of the hyperfine field due to the presence of Co atoms in the (Fe,Co) 2 B phase, where additional defect positions are formed by Re and W. Radio-frequency Mössbauer studies showed that (Fe 0.7 Co 0.3 ) 2 B and the W-substituted sample began to crystallize when exposed to an radio frequency field of 12 Oe, indicating that the amorphous phase is stabilized by Re substitution. Improvement of thermal stability of (Fe 0.675 Co 0.275 Re 0.05 ) 2 B alloy is consistent with the results of differential scanning calorimetry and thermomagnetic measurements.

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“…It is noted that, compared with those obtained based on DFT calculations, the machine learned values are more accurate. [7][8][9] The valence electron features are still assigned with the highest importance of 41%, while that for the magnetic moment of the constituting elements increases to 25% corresponding to the linear relationship between magnetic moment per atom with the total magnetization. Interestingly, the importance of SOAP drops to only 9%, indicating that the local crystalline environment has less importance when FM ordering is determined.…”

Section: Regressionmentioning

confidence: 99%

“…This approach fails even for elemental metal like Co and Ni, due to the strong itinerant nature of magnetism therein. 7,8 Moreover, DFT is not sufficient in describing the strongly correlated 4f electrons in rare-earths, 9 while the orbital dependent functional (e.g., DFT+U) treatment is often chosen to fit to experiments. The state-of-the-art DFT plus dynamical mean field theory (DMFT) method can be applied to tackle the electronic correlation problem but is numerically expensive.…”

Section: Introductionmentioning

confidence: 99%

An accelerating approach of designing ferromagnetic materials via machine learning modeling of magnetic ground state and Curie temperature

Long

Fortunato

Zhang

et al. 2021

Materials Research Letters

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Magnetic materials have a plethora of applications from information technologies to energy harvesting. However, their functionalities are often limited by the magnetic ordering temperature. In this work, we performed random forest on the magnetic ground state and the Curie temperature (T C) to classify ferromagnetic and antiferromagnetic compounds and to predict the T C of the ferromagnets. The resulting accuracy is about 87% for classification and 91% for regression. When the trained model is applied to magnetic intermetallic materials in Materials Project, the accuracy is comparable. Our work paves the way to accelerate the discovery of new magnetic compounds for technological applications. IMPACT STATEMENT A machine learning model to classify ferromagnetic and antiferromagnetic compounds and to predict the Curie temperature of the ferromagnets is constructed, which could accelerate the discovery of new magnetic compounds.

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Magnetic and magnetocaloric properties of the Co2-xMn B system by experiment and density functional theory

Cited by 11 publications

References 41 publications

Effect of N, C and B interstitials on the structural and magnetic properties of alloys with Cu$_3$Au-structure

Effect of N, C and B interstitials on the structural and magnetic properties of alloys with Cu$_3$Au-structure

Structural transformation and magnetic properties of (Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with 5$d$ elements: A combined first-principles and experimental study

An accelerating approach of designing ferromagnetic materials via machine learning modeling of magnetic ground state and Curie temperature

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