Effective interaction model for coupled magnetism and phase stability in bcc Fe-Co systems

Tran, Van-Truong; Fu, Chu‐Chun; Schneider, Annemarie

doi:10.1016/j.commatsci.2020.109906

Cited by 12 publications

(7 citation statements)

References 66 publications

(38 reference statements)

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“…We adopt a model Hamiltonian similar to those used to investigate magnetic properties, phase stability [55][56][57]61], and vacancy formation and diffusion properties [24,58,79] of Fe-based systems. The Hamiltonians for the present pure systems are as follows:…”

Section: B Effective Interaction Models (Eim)mentioning

confidence: 99%

“…For example, the vacancy formation energy obtained for NM fcc Fe is 2.37 eV, much higher than the experimental values (1.40-1.83 eV [29][30][31][32][33]). More advanced descriptions of PM state properties can be achieved via the disordered local moment (DLM) approach [47,48], the spin-wave method [49], spin dynamics [50][51][52], spin-lattice dynamics [53,54], and Monte Carlo simulations based on magnetic model Hamiltonians [55][56][57][58] (see Ref. [59] for a recent review), etc.…”

Section: Introductionmentioning

confidence: 99%

“…[59] for a recent review), etc. Most of these studies [47][48][49][50][51][52][53][54][55][56][57][58]60,61] only considered defectfree systems. Regarding the vacancy properties in the PM state, most of the investigations addressed bcc Fe [20][21][22][23][24], while there are very few such studies of fcc Fe [62] or fcc Ni.…”

Section: Introductionmentioning

confidence: 99%

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Effects of magnetic excitations and transitions on vacancy formation: Cases of fcc Fe and Ni compared to bcc Fe

Fu²,

Schneider³

2021

Phys. Rev. B

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Vacancy is one of the most frequent defects in metals. We study the impacts of magnetism on vacancy formation properties in fcc Ni, and in bcc and fcc Fe, via density functional theory (DFT) and effective interaction models combined with Monte Carlo simulations. Overall, the predicted vacancy formation energies and equilibrium vacancy concentrations are in good agreement with experimental data, available only at the high-temperature paramagnetic regime. Effects of magnetic transitions on vacancy formation energies are found to be more important in bcc Fe than in fcc Fe and Ni. The distinct behavior is correlated to the relative roles of longitudinal and transversal spin excitations. At variance with the bcc-Fe case, we note a clear effect of longitudinal spin excitations on the magnetic free energy of vacancy formation in fcc Fe and Ni, leading to its steady variation above the respective magnetic transition temperature. Below the Néel point, such effect in fcc Fe is comparable but opposite to the one of the transversal excitations. Regarding fcc Ni, although neglecting the longitudinal spin excitations induces an overestimation of the Curie temperature by 220 K, no additional effect is visible below the Curie point. The distinct effects on the three systems are closely linked to DFT predictions of the dependence of vacancy formation energy on the variation of local magnetic-moment magnitudes and orientations.

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Section: B Effective Interaction Models (Eim)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of magnetic excitations and transitions on vacancy formation: Cases of fcc Fe and Ni compared to bcc Fe

Fu²,

Schneider³

2021

Phys. Rev. B

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“…A more sophisticated magnetic cluster expansion (MCE) approach was later applied by Lavrentiev et al to the study of Fe-Ni 36 , Fe-Cr 37 and Fe-Ni-Cr 38 alloys. Similar models were also developed by Ruban et al 28 for Fe-Cr and by Tran et al 39 for Fe-Co alloys. These models are generally used in on-lattice Monte Carlo (MC) simulations for finite temperature studies, Chapman et al 40 have recently adapted the MCE model by Lavrentiev et al 37 for spin-lattice dynamics simulations.…”

Section: Introductionmentioning

confidence: 68%

Ab-initio based models for temperature-dependent magneto-chemical interplay in bcc Fe-Mn alloys

Schneider,

Fu,

Waseda

et al. 2020

Preprint

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Body-centered cubic (bcc) Fe-Mn systems are known to exhibit a complex and atypical magnetic behaviour from both experiments and 0 K electronic-structure calculations, which is due to the half-filled 3d-band of Mn. We propose effective interaction models for these alloys, which contain both atomic spin and chemical variables. They were parameterized on a set of key density functional theory (DFT) data, with the inclusion of non-collinear magnetic configurations being indispensable. Two distinct approaches, namely a knowledge-driven and a machine-learning approach have been employed for the fitting. Employing these models in atomic Monte Carlo simulations enables the prediction of magnetic and thermodynamic properties of the Fe-Mn alloys, and their coupling, as functions of temperature. This includes the decrease of Curie temperature with increasing Mn concentration, the temperature evolution of the mixing enthalpy and its correlation with the alloy magnetization. Also, going beyond the defect-free systems, we determined the binding free energy between a vacancy and a Mn atom, which is a key parameter controlling the atomic transport in Fe-Mn alloys.

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“…In this work, they are unified and extended as a single EIM for the whole composition range of fcc Fe-Ni alloys. The Hamiltonian form is similar to the previous ones used to investigate magnetic properties, phase stability [24,73,74] and vacancy formation and diffusion properties [13,59] of the Fe-based systems. The current EIM has the following form:…”

Section: B Effective Interaction Modelmentioning

confidence: 99%

Magnetochemical effects on phase stability and vacancy formation in fcc Fe-Ni alloys

Li,

Fu,

Nastar

et al. 2022

Preprint

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We investigate phase stability and vacancy formation in fcc Fe-Ni alloys over a broad compositiontemperature range, via a density functional theory parametrized effective interaction model, which includes explicitly spin and chemical variables. On-lattice Monte Carlo simulations based on this model are used to predict the temperature evolution of the magnetochemical phase. The experimental composition-dependent Curie and chemical order-disorder transition temperatures are successfully predicted. We point out a significant effect of chemical and magnetic orders on the magnetic and chemical transitions, respectively. The resulting phase diagram shows a magnetically driven phase separation around 10-40% Ni and 570-700 K, between ferromagnetic and paramagnetic solid solutions, in agreement with experimental observations. We compute vacancy formation magnetic free energy as a function of temperature and alloy composition. We identify opposite magnetic and chemical disordering effects on vacancy formation in the alloys with 50% and 75% Ni. We find that thermal magnetic effects on vacancy formation are much larger in concentrated Fe-Ni alloys than in fcc Fe and Ni due to a stronger magnetic interaction.

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Effective interaction model for coupled magnetism and phase stability in bcc Fe-Co systems

Cited by 12 publications

References 66 publications

Effects of magnetic excitations and transitions on vacancy formation: Cases of fcc Fe and Ni compared to bcc Fe

Effects of magnetic excitations and transitions on vacancy formation: Cases of fcc Fe and Ni compared to bcc Fe

Ab-initio based models for temperature-dependent magneto-chemical interplay in bcc Fe-Mn alloys

Magnetochemical effects on phase stability and vacancy formation in fcc Fe-Ni alloys

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