Longitudinal spin fluctuation contribution to thermal lattice expansion of paramagnetic Fe

Dong, Zhihua; Li, Wei; Chen, Dengfu; Schönecker, Stephan; Long, Mujun; Vitos, Levente

doi:10.1103/physrevb.95.054426

Cited by 33 publications

(28 citation statements)

References 54 publications

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“…The paramagnetic state is modeled with the disordered local moment (DLM) approximation [22]. At high temperatures, the spin magnetic moment of electrons would fluctuate around its expected value, which affects the magnetic susceptibility and Curie temperature of the system to a certain extent [16]. Current research usually takes 1043 K as the temperature of the magnetic transition of iron [6,23], ignoring the effect of electron spin fluctuations on the Curie temperature.…”

Section: Ab Initio Computational Methodsmentioning

confidence: 99%

“…In summary, ab initio calculation at high temperature relies on a large number of computing resources, and the calculation process is quite complicated. The volume expansion is an important temperature effect from lattice anharmonicity [16]. Actually, the thermal lattice expansion is recognized as the main parameter influencing the temperature [14].…”

Section: Introductionmentioning

confidence: 99%

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Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory

Long

Zhang

et al. 2020

Metals

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Elucidating the evolution law of the elastic properties of the matrix phase is of great significance for the control of steel properties and quality during continuous casting and subsequent heat treatment. In this paper, thermal expansion experiments and ab initio calculations are used to study the elastic properties of the interstitial free (IF) steel matrix phase in different magnetic states and crystal structures. The results show that the bulk modulus B and the tetragonal shear elastic constant C’ for the entire temperature range decrease with increasing temperature, but C44 is the opposite. While from paramagnetic (PM) to ferromagnetic (FM) state, C’(C44) have changed ~188% (~27%), B increases by ~55% during the crystal structure change (fcc→bcc). With the FM to PM state, the Zener anisotropy parameter increases sharply, and Young’s modulus decreases significantly in the [001] direction; the maximum difference is ~76 GPa. The evolution rate of average Young’s modulus in single bcc-phase FM (fcc-phase PM) range reaches ~5.5(~5.6) × 10−2 GPa K−1. The research provides an effective method for ab initio calculation of the elastic properties of interstitial free and ultra-low carbon steels at high temperature, also furnishing a basis for the application of ab initio calculations to the high temperature performance of steel materials.

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Section: Ab Initio Computational Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory

Long

Zhang

et al. 2020

Metals

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“…Longitudinal spin fluctuations (LSF) theory is an active research topic [67][68][69][70][71]. LSF are related to electronic excitations in a more intimate way than magnetic transverse degrees of freedom, and they are typically faster than these last ones; nonetheless, semi-classical models that allow for the approximate inclusion of this Theoretical methods effect in the framework of the Heisenberg Hamiltonian have been developed [68,72].…”

Section: Longitudinal Spin Fluctuationsmentioning

confidence: 99%

“…It has been used to explain properties of the ferromagnetic elemental solids (bcc Fe, Ni and Co) [68][69][70][71] and Heusler alloys [67], to name a few. The LSF energy shows very different behavior for itinerant and localized moments system in a paramagnetic environment, as can be seen in Fig.…”

Section: Longitudinal Spin Fluctuationsmentioning

confidence: 99%

Structural and magnetic disorder in crystalline materials : a first principles study

Gambino

2019

Linköping Studies in Science and Technology. Licentiate Thesis

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This thesis is just an intermediate achievement on the long journey towards the PhD degree; nonetheless, many people need to be acknowledged for their help and their patience that enabled me to get, at least, to this point. Above all, I thank with the most gratitude my supervisor Dr. Björn Alling for teaching me how to think in physics terms, being always present, and leading my scientific growth. I still have a lot to learn, but with your guidance I am sure it is going to work out. Thanks as well for the frequent updates on Swedish politics. A great thank goes to Prof. Igor Abrikosov for the chance he gave me to stay at Linköping University, and suggesting me to contact Björn for the PhD position I am currently occupying. I thank particularly Dr. Davide Sangiovanni for the many discussions and updates on ongoing projects, which acquire a very pleasant taste when told in Italian. A big thank as well to Dr. Irina Stockem for her support with the ASD-AIMD code and patience with my annoying and recurrent requests; also, thank you very much for hosting me at MPIE during my visits. I must acknowledge Johan Klarbring for useful discussions and suggestions on project-related topics, and together with Johan Jönsson for bearing me at the APS 2019 March Meeting. Thanks to Johan Tidholm for the good time in the shared office (and the "Friday after 3 pm" ritual), Dr. Marcus Ekholm for suggestion of the SCAN project, and all the other members of the Theoretical Physics group here at Linköping University.

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“…The FMA can be used in combination with the OSA, Eq. 8; in fact, this combination was employed in recent investigations of the impact of LSFs on the elastic constants and the thermal expansion of PM fcc and bcc Fe [30,40]. In Sec.…”

Section: Fluctuating Medium Approximationmentioning

confidence: 99%

Elastic properties of paramagnetic austenitic steel at finite temperature: Longitudinal spin fluctuations in multicomponent alloys

et al. 2017

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We propose a first-principles framework for longitudinal spin fluctuations (LSFs) in disordered paramagnetic (PM) multicomponent alloy systems and apply it to investigate the influence of LSFs on the temperature dependence of two elastic constants of PM austenitic stainless steel Fe15Cr15Ni. The magnetic model considers individual fluctuating moments in a static PM medium with first-principles-derived LSF energetics in conjunction with describing chemical disorder and randomness of the transverse magnetic component in the single-site alloy formalism and disordered local moment (DLM) picture. A temperature-sensitive mean magnetic moment is adopted to accurately represent the LSF state in the elastic-constant calculations. We make evident that magnetic interactions between an LSF impurity and the PM medium are weak in the present steel alloy. This allows gaining accurate LSF energetics and mean magnetic moments already through a perturbation from the static DLM moments instead of a tedious self-consistent procedure. We find that LSFs systematically lower the cubic shear elastic constants c and c 44 by ∼6 GPa in the temperature interval 300-1600 K, whereas the predominant mechanism for the softening of both elastic constants with temperature is the magneto-volume coupling due to thermal lattice expansion. We find that non-negligible local magnetic moments of Cr and Ni are thermally induced by LSFs, but they exert only a small influence on the elastic properties. The proposed framework exhibits high flexibility in accurately accounting for finite-temperature magnetism and its impact on the mechanical properties of PM multicomponent alloys.

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Longitudinal spin fluctuation contribution to thermal lattice expansion of paramagnetic Fe

Cited by 33 publications

References 54 publications

Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory

Ab Initio Calculations on Elastic Properties of IF Steel Matrix Phase at High Temperature Based on Lattice Expansion Theory

Structural and magnetic disorder in crystalline materials : a first principles study

Elastic properties of paramagnetic austenitic steel at finite temperature: Longitudinal spin fluctuations in multicomponent alloys

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