Spin spiral ground state of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>-iron

Knöpfle, K. T.; Sandratskii, L. M.; Kübler, J.

doi:10.1103/physrevb.62.5564

Cited by 143 publications

(126 citation statements)

References 14 publications

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“…39 In the calculation of the density gradient, we used ͑UU † ͒ 11 and ͑UU † ͒ 22 corresponding to the diagonal elements of the density matrix in the local-axis representation, and the resulting matrix for the exchangecorrelation potential was regarded diagonal in the same representation. 40 In this treatment of the exchangecorrelation energy, variations of the density gradient resulting from the spatial dependence of ͑r͒ and ͑r͒ are disregarded, and E xc only depends on n͑r͒ and m͑r͒. 41 With this setting for the electronic-structure calculations, we reproduced well the properties of the isolated oxygen molecule.…”

Section: A Model System and Technical Aspectssupporting

confidence: 48%

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Oda

Pasquarello

2004

Phys. Rev. B

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We perform first-principles molecular dynamics of liquid oxygen in which the magnetic structure evolves according to a generalized density-functional scheme allowing for noncollinear spin configurations. We investigate both structural correlations between the orientations of the molecular axes and magnetic correlations between the orientations of the molecular magnetic moments, demonstrating a clear relation between the local molecular configuration and the relative magnetic arrangement. The nuclear structure factor obtained from the simulation is found to agree well with the experimental one. The calculated magnetic structure factor shows antiferromagnetic correlations between molecules in the first shell, in accord with spin-polarized neutron scattering measurements. We observe the formation of dynamically coupled molecules, known as O 4 units, in which the molecular moments are aligned in an antiferromagnetic fashion. An analysis based on the life time of such units, revealed that in most cases the O 4 units occur as transient configurations during collisions. However, we also observed a small fraction of O 4 units surviving for relatively long periods. To account for electronic excitations which are missed in our density-functional scheme, we complement our description with a mean field model for the thermal fluctuations of the magnetic structure. The combined scheme is found to improve the description of the magnetic neutron structure factor and allows us to study the dependence of the magnetic susceptibility on temperature.

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Section: A Model System and Technical Aspectssupporting

confidence: 48%

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Oda

Pasquarello

2004

Phys. Rev. B

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“…6,13,14,15,16,17,18,19,20 . Knöpfle and co-workers 6 , who used GGA or LDA and a full-potential implementation of Density Functional Theory found that the ground state was indeed a spiral with the correct pitch vector. But since the Augmented Spherical Wave (ASW) method tends to overestimate the Typeset by REVT E X atomic volume, it is difficult to extract what their equilibrium lattice constant a 0 might be.…”

Section: Molecular Dynamics Packages Based On Density Functional Theomentioning

confidence: 99%

“…We believe it is useful to supply first a backbone of non-collinear DFT 7,8 , which will help us discuss similarities and differences with the latest approaches 6 .…”

Section: Theoretical Backbonementioning

confidence: 99%

First principles simulations of the magnetic and structural properties of Iron

et al. 2004

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We have implemented non-collinear GGA and a generalized Bloch's theorem to simulate unconmensurate spiral arrangements of spins in a Density Functional Theory code based on localized wave functions. We have subsequently performed a thorough study of the different states of bulk Iron. We determine the minimal basis set required to obtain reliable orderings of ground and excited states. We find that the most stable fcc phase is a spiral with an equilibrium lattice constant 3.56Å.

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“…These experiments have shown that γ -Fe displays a noncollinear, spiral magnetic structure. 11,12 The numerous first-principles studies carried out to search for the γ -Fe ground state [13][14][15][16][17][18][19][20] showed many competing magnetic structures lying between 0.08 and 0.15 eV/atom above the bcc ferromagnetic ground state, thus complicating the choice of a relevant reference state for calculations of physical properties in γ -Fe. Another critical issue is to model the PM state in γ -Fe since austenitic SS are PM at temperatures where nuclear reactors operate.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

Piochaud¹,

Klaver²,

Adjanor³

et al. 2014

Phys. Rev. B

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The influence of the local environment on vacancy and self-interstitial formation energies has been investigated in a face-centered-cubic (fcc) Fe-10Ni-20Cr model alloy by analyzing an extensive set of first-principle calculations based on density functional theory. Chemical disorder has been considered by designing special quasirandom structures and four different collinear magnetic structures have been investigated in order to determine a relevant reference state to perform point defect calculations at 0 K. Two different convergence methods have also been used to characterize the importance of the method on the results. Although our fcc Fe-10Ni-20Cr would be better represented in terms of applications by the paramagnetic state, we found that the antiferromagnetic single-layer magnetic structure was the most stable at 0 K and we chose it as a reference state to determine the point defect properties. Point defects have been introduced in this reference state, i.e., vacancies and Fe-Fe, Fe-Ni, Fe-Cr, Cr-Cr, Ni-Ni, and Ni-Cr dumbbell interstitials oriented either parallel or perpendicular to the single layer antiferromagnetic planes. Each point defect studied was introduced at different lattice sites to consider a sufficient variety of local environments and analyze its influence on the formation energy values. We have estimated the point defect formation energies with linear regressions using variables which describe the local environment surrounding the point defects. The number and the position of Ni and Cr first nearest neighbors to the point defects were found to drive the evolution of the formation energies. In particular, Ni is found to decrease and Cr to increase the vacancy formation energy of the model alloy, while the opposite trends are found for the dumbbell interstitials. This study suggested that, to a first approximation, the first nearest atoms to point defects can provide reliable estimates of point defect formation energies.

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Spin spiral ground state ofγ-iron

Cited by 143 publications

References 14 publications

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

Noncollinear magnetism in liquid oxygen: A first-principles molecular dynamics study

First principles simulations of the magnetic and structural properties of Iron

First-principles study of point defects in an fcc Fe-10Ni-20Cr model alloy

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