Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Hegde, Omkar; Grabowski, Maximilian; Zhang, Xie; Waseda, Osamu; Hickel, Tilmann; Freysoldt, Christoph; Neugebauer, Jörg

doi:10.1103/physrevb.102.144101

Cited by 17 publications

(14 citation statements)

References 55 publications

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“…All values are in eV. [46], but more interestingly agrees with the vacancy formation energy from DFT+DMFT calculations with some local lattice relaxations allowed [56] and, as previously mentioned, with the SSA relaxation method of Hegde et al [124]. These results and the results from literature are summarized in Table 6.1.…”

Section: Application To Defects In Bcc Fe and To Fe 1-x Cr Xsupporting

confidence: 87%

“…More recently, Hegde et al [124] developed a method similar to the present DLM relaxation, but based on the use of magnetic SQS supercells and the SSA averaging of the forces. In this SSA relaxation method, several relaxations of a magnetic SQS supercell with the vacancy placed in different positions are run in parallel, and at each step the forces from each calculation are averaged together and symmetrized according to the SSA method.…”

Section: Dlm Relaxationmentioning

confidence: 99%

“…To show that the experimentally determined atomic positions are of relevance, a DLM relaxation of the structure was performed with a modified version of the DLM relaxation algorithm. In this case, a method more similar to the one by Hegde et al [124] was employed, using at each step of the relaxation ten different MSM configurations randomly drawn and averaging the forces from these calculations at each atomic site without account of symmetry. The final structure displays local relaxations that are virtually undetectable by experimental techniques, although the atomic forces strongly decrease during the relaxation, supporting the experimental conclusions on the structure of this compound.…”

Section: Fe 3 Comentioning

confidence: 99%

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Ab Initio Modeling of Magnetic Materials in the High-Temperature Paramagnetic Phase

Gambino

2021

Linköping Studies in Science and Technology. Dissertations

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The introductory part of this thesis gives an overview of the theories and methods employed to study magnetic materials in their high-temperature paramagnetic phase with first principles techniques, followed by the main results from my own work regarding the interplay between magnetism and other degrees of freedom, namely structural and vibrational degrees of freedom. Extensive parts of these chapters are taken from my Licenciate Thesis (No. 1837, Linköping Studies in Science and Technology), published in 2019. During the course of research underlying this thesis, I was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. xv xviNo one can go through the long journey of the PhD studies alone; here I want to thank all those that helped me achieve this goal.Not only because it is due, but because I really want to, I first must acknowledge my supervisor Björn Alling. You have been a true advisor, always putting my personal development first. I feel like I grew a lot in these four years and a half, both personally and academically, and I really need/want to thank you for this.Many thanks to the Head of the Theoretical Physics Division Igor Abrikosov for initially offering me the opportunity to be part of this group, and to my co-supervisor Marcus Ekholm for the help and spontaneous projects that appeared on the way. I would like to thank all the members of the Theoretical Physics Division, in particular Johan K., Johan T., Johan J., Joel D. and Luis C., for sharing lively physics discussions, conference experiences (sorry for those) and more informal, very fun gatherings. A special mention to Davide S., who introduced me to the world of research quite a few years ago at this point: it is always a pleasure to discuss with you and see your passion in what you do!To achieve a goal such as a PhD degree, one needs to disconnect every now and then from work. This task has been greatly achieved thanks to many, many people from the international community that gravitates around IFM, and beyond. Many people have passed in these years, and I will for sure forget to mention someone for which I am very sorry, nonetheless thanks to

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Section: Application To Defects In Bcc Fe and To Fe 1-x Cr Xsupporting

confidence: 87%

Section: Dlm Relaxationmentioning

confidence: 99%

Section: Fe 3 Comentioning

confidence: 99%

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Ab Initio Modeling of Magnetic Materials in the High-Temperature Paramagnetic Phase

Gambino

2021

Linköping Studies in Science and Technology. Dissertations

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“…Experimental measurements of selfand solute diffusion coefficients in bcc Fe revealed strong effects of magnetism [9,[14][15][16][17]. These experimental evidences have motivated various recent theoretical studies [18][19][20][21][22][23][24]. However, very little is known about such effects on the vacancy-related properties in other magnetic systems (for example fcc Fe, fcc Ni, and bcc Cr) that exhibit important longitudinal spin fluctuations at finite temperatures [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…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. Furthermore, the effects of longitudinal spin fluctuations, which can be important in the PM regime, are often neglected.…”

Section: Introductionmentioning

confidence: 99%

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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A self-adaptive first-principles approach for magnetic excited states

Cai,

Wang,

et al. 2023

Quantum Front

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The profound impact of excited magnetic states on the intricate interplay between electron and lattice behaviors in magnetic materials is a topic of great interest. Unfortunately, despite the significant strides that have been made in first-principles methods, accurately tracking these phenomena remains a challenging and elusive task. The crux of the challenge that lies before us is centered on the intricate task of characterizing the magnetic configuration of an excited state, utilizing a first-principle approach that is firmly rooted in the ground state of the system. We propose a versatile self-adaptive spin-constrained density functional theory formalism. By iteratively optimizing the constraining field alongside the electron wave function during energy minimization, we are able to obtain an accurate potential energy surface that captures the longitudinal and transverse variations of magnetization in itinerant ferromagnetic Fe. Moreover, this technique allows us to identify the subtle coupling between magnetic moments and other degrees of freedom by tracking energy variation, providing new insights into the intricate interplay between magnetic interactions, electronic band structure, and phonon dispersion curves in single-layered $\mathrm{CrI} _{3}$ CrI 3 . This new methodology represents a significant breakthrough in our ability to probe the complex and multifaceted properties of magnetic systems.

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Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism

Cited by 17 publications

References 55 publications

Ab Initio Modeling of Magnetic Materials in the High-Temperature Paramagnetic Phase

Ab Initio Modeling of Magnetic Materials in the High-Temperature Paramagnetic Phase

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

A self-adaptive first-principles approach for magnetic excited states

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