Evolution of Intrinsic Magnetic Properties in L1
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 Alloys Doped with Substitutional Atoms and Correlated Mechanism: Experimental and Theoretical Studies

Zhao, Shuang; Wu, Yuehong; Jiao, Zhengying; Jia, Yan; Xu, Yichen; Wang, Jingmin; Zhang, Tianli; Jiang, Chengbao

doi:10.1103/physrevapplied.11.064008

Cited by 16 publications

(7 citation statements)

References 50 publications

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“…9 . The 3 d orbit of Mn and 3 p orbit of Al is hybrid above the Fermi energy, as previous reports have suggested 24 . Therefore, we conclude that the mechanism of antiferromagnetism in τ-phase is the super-exchange interaction between Mn atoms via p -electrons of Al atoms.…”

Section: First Principles Electronic-structure Calculations Of L1 supporting

confidence: 70%

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Sato

Irie

Nagamine

et al. 2020

Sci Rep

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Manganese (Mn)-based strong magnets have long been a challenge because their 3 d half-filled nature, owing to the close proximity of Mn atoms, results in antiferromagnetic ordering. Among various Mn magnetic materials, L1 0 -MnAl (τ-phase) has received much attention since it shows ferromagnetism at a high Curie temperature despite the very short Mn–Mn distance. However, because of the difficult synthesis of the stoichiometric and perfectly ordered τ-phase, its intrinsic magnetic properties and mechanism are unclear. Here, we show the first observation of antiferromagnetism, having sixfold magnetic superstructure along the c-axis, in stoichiometric and chemically ordered τ-phase. Moreover, we found that super-exchange interaction between Mn atoms via p -electrons of Al atoms causes antiferromagnetism in τ-phase. The ferromagnetism in the conventional Mn-rich τ-phase results from the suppression of the super-exchange interaction due to the substitution the excess Mn atoms for the Al atoms. The current study of Mn-based magnetic materials mainly focuses on the lattice constant engineering based on the simple Beth-Slater picture of direct exchange. These findings present effective ways to obtain high magnetization without antiferromagnetic ordering.

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Section: First Principles Electronic-structure Calculations Of L1 supporting

confidence: 70%

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Sato

Irie

Nagamine

et al. 2020

Sci Rep

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“…This can be achieved by two common methods: (i) quenching from the melt or from high temperatures (around 1100°C) to stabilize the parent e-phase (hexagonal structure-HCP) followed by annealing at moderate temperatures (around 500°C); (ii) high temperature annealing followed by controlled cooling,whichresults in t-phase nucleation and growth during this last step. As mentioned, the ferromagnetic phase is metastable, which means that long annealing times or high temperatures can lead to decomposition of the t-phase and nucleation of the non-magnetic stable g 2 and b-phases [20,22,23]. The formation of the ordered L1 0 t-phase, from the parent chemically disordered HCP e-phase,is reported to happen through two main mechanisms: massive and displacive.…”

Section: Introductionmentioning

confidence: 98%

“…To increase the stability of the ferromagnetic phase, carbon is often added as interstitial dopant to the t-phase compositional range, Mn 50+x Al 50Àx (51 x 58), at the expenses of decreasing the Curie temperature (T C ) from 630 to 570 K [20,22]. But only phase purity is not a guarantee for optimized magnetic properties, since different manufacturing processes affect the microstructure and, consequently, the extrinsic magnetic properties.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and magnetic properties of Mn-Al-C permanent magnets produced by various techniques

et al. 2021

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Bulk Mn52Al46C2 in τ-phase was prepared by vacuum induction melting and used as precursor for the production bulk permanent magnets by suction casting and hot-extrusion. Part of the precursor alloy was mechanically milled into a τ-phase powder and used as precursor for production of samples by electron beam melting, hot-compaction and high pressure torsion processes. The microstructure and magnetic properties of all samples were investigated and correlated. It was found that the mechanical deformation enhances coercivity, up to 0.58 T, while the absence of this strain is beneficial for magnetization. Among the observed techniques, hot extrusion and high pressure torsion have shown promising possibilities to further develop Mn-Al-C as permanent magnets. However, it should be taken into account the challenges related to design a proper processing window for hot extrusion and the limitation of HPT regarding the absence of texture.

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“…Mix et al demonstrated that Ga additions stabilize the ferromagnetic τ phase in Mn-Al alloys and also found that the non-magnetic γ 2 phase directly transformed into a ferromagnetic τ phase when annealing at 500 °C [14,15]. Zhao, S. et al investigated ternary Mn-Al-X alloys (X = Cu, Co, and Ga) experimentally and performed first principles computations of Mn-Al-X supercells based on density functional theory and suggested from the resulting energy calculations that the Ga prefers to occupy the (1/2,1/2,1/2) site, while Cu and Co occupy the (0,0,0) sites [16]. Zhao also reported experiments in which Ga additions increased the intrinsic magnetic properties (i.e., M s , K 1 , T c ) and improved the stabilization of the τ phase compared to the binary Mn-Al providing supporting evidence of gallium's preferred site occupancy within the crystal lattice unit cell.…”

Section: Introductionmentioning

confidence: 99%

Transformation Pathways of Ferromagnetic Mn-Al-Ga-Ni

et al. 2023

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This study investigates the impact of alloying Mn-Al-Ga with 3 at.-% Ni and the stability and formation mechanisms of the τ phase and the resulting magnetic properties. The stabilizing effect of Ga on the τ phase was verified, and the ternary alloy’s magnetization was measured up to M2T=482kA/m−1. The phase transformation from γ2 to τ in ternary Mn-Al-Ga was demonstrated microscopically. The solubility limit of Ni into the τ phase was exceeded at 3 at.-% and a primitive cubic κ phase formed. The Ni addition stabilized the τ phase. The highest magnetization at 2 T for the Mn52Al39.4Ga5.6Ni3 alloy was M2T=416kA/m−1 . A new transformation pathway was demonstrated by first annealing the Mn-Al-Ga-Ni alloy at 800 °C for 24 h, which forms a nearly single κ phase, which is followed by a second anneal at 500 °C for 24 h at which the phase τ formed with some remaining κ phase. This is a new transformation mechanism since it involves a phase reaction from κ to τ. The energy product of the Mn-Al-Ga-Ni alloy exceeded that of the ternary Mn-Al-Ga alloy by a factor of 4.5. The κ-phase particles in the Mn-Al-Ga-Ni alloy hinder magnetic domain boundary motion, thus providing a method for magnetic hardening and increasing the energy product.

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Evolution of Intrinsic Magnetic Properties in L1 ₀ Mn−Al Alloys Doped with Substitutional Atoms and Correlated Mechanism: Experimental and Theoretical Studies

Cited by 16 publications

References 50 publications

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Microstructure and magnetic properties of Mn-Al-C permanent magnets produced by various techniques

Transformation Pathways of Ferromagnetic Mn-Al-Ga-Ni

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Evolution of Intrinsic Magnetic Properties in L1 0 Mn−Al Alloys Doped with Substitutional Atoms and Correlated Mechanism: Experimental and Theoretical Studies

Cited by 16 publications

References 50 publications

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Antiferromagnetism in perfectly ordered L10-MnAl with stoichiometric composition and its mechanism

Microstructure and magnetic properties of Mn-Al-C permanent magnets produced by various techniques

Transformation Pathways of Ferromagnetic Mn-Al-Ga-Ni

Contact Info

Product

Resources

About

Evolution of Intrinsic Magnetic Properties in L1 ₀ Mn−Al Alloys Doped with Substitutional Atoms and Correlated Mechanism: Experimental and Theoretical Studies