Theory of Magnetic and Structural Ordering in Iron

Wang, C. S.; Klein, B. M.; Krakauer, Henry

doi:10.1103/physrevlett.54.1852

Cited by 474 publications

(162 citation statements)

References 26 publications

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“…Although it is generally accepted that GGA can give a better description of iron in many aspects, 36 it happens that the few calculations of J ij ef f we found in the literature are all performed with LDA. To establish GGA for our calculations, we perform a comparison of the J ij ef f obtained from both methods for the experimental equilibrium lattice constant ͑2.8665 Å͒.…”

Section: Resultsmentioning

confidence: 99%

Exchange interaction function for spin-lattice coupling in bcc iron

Wang

Woo

2010

Phys. Rev. B

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Functional representations of the spin polarization and the exchange interaction in terms of the lattice configuration is necessary to model the dynamics of the coupled spin and lattice subsystems in large-scale atomistic simulation of magnetic materials. Data needed for this purpose have only existed in the regime of small displacements from the equilibrium perfect lattice configurations. In this paper, we report and discuss the results of our first-principles calculations for bcc iron over a wide range of lattice constants using the magnetic force theorem and the one-electron Green's function. Despite the relatively complex functional form of the exchange interaction function for bcc iron our results show that it can be expressed as a superposition of Bethe-Slater-type curves representing interatomic exchange interaction of the 3d electrons.

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Section: Resultsmentioning

confidence: 99%

Exchange interaction function for spin-lattice coupling in bcc iron

Wang

Woo

2010

Phys. Rev. B

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“…Iron has been studied widely with first-principles theoretical approaches because of its geophysical importance and the well known failure of the local density approximation (LDA) to the exchange-correlation potential to predict the ferromagnetic bcc ground state 17 . This failure was a major impetus in the development of the generalized gradient approximation (GGA) [18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

First-principles elastic constants for the hcp transition metals Fe, Co, and Re at high pressure

1999

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The elastic constant tensors for the hcp phases of three transition metals (Co, Re, and Fe) are computed as functions of pressure using the Linearized Augmented Plane Wave method with both the local density and generalized gradient approximations. Spin-polarized states are found to be stable for Co (ferromagnetic) and Fe (antiferromagnetic at low pressure). The elastic constants of Co and Re are compared to experimental measurements near ambient conditions and excellent agreement is found. Recent measurements of the lattice strain in high pressure experiments when interpreted in terms of elastic constants for Re and Fe are inconsistent with the calculated moduli.

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“…1 [34]. In addition, this exchange-correlation functional is known to give a superior description of the equilibrium volumes and energetics of metals and alloys to that of the local density approximation (LDA), especially for the magnetic elements where LDA even gives the wrong ground-state structure of Fe [35].…”

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confidence: 99%

Criteria for Predicting the Formation of Single-Phase High-Entropy Alloys

et al. 2015

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High-entropy alloys constitute a new class of materials whose very existence poses fundamental questions regarding the physical principles underlying their unusual phase stability. Originally thought to be stabilized by the large entropy of mixing associated with their large number of components (five or more), these alloys have attracted attention for their potential applications. Yet, no model capable of robustly predicting which combinations of elements will form a single phase currently exists. Here, we propose a model that, through the use of high-throughput computation of the enthalpies of formation of binary compounds, predicts specific combinations of elements most likely to form single-phase, highentropy alloys. The model correctly identifies all known single-phase alloys while rejecting similar elemental combinations that are known to form an alloy comprising multiple phases. In addition, we predict numerous potential single-phase alloy compositions and provide three tables with the ten most likely five-, six-, and seven-component single-phase alloys to guide experimental searches. The term high-entropy alloy (HEA) has come to signify nontraditional alloy systems composed of five or more elements at, or near, equiatomic ratio that form random, single-phase solid solutions on simple underlying facecentered-cubic (fcc) and body-centered-cubic (bcc) lattices [1][2][3][4][5][6][7][8][9][10][11]. HEAs stand in sharp contrast to traditional metal alloys that are typically based on one or two primary elements and where addition of further alloying elements often leads to the formation of new phases. Clearly, the existence of HEAs poses important questions regarding the driving mechanism for their unexpected stability and how to identify the specific combinations of elements that are most likely to form a single-phase HEA.Although there are several proposals regarding the stability of HEAs, much of the existing work uses semiempirical approaches based, for example, on HumeRothery rules, thus focusing on the differences of the atomic sizes (δ), electronegativities (Δχ), and electron-toatom ratio (e=a) [12][13][14][15][16][17]. Some approaches utilize calculation of phase diagrams methods [18], while others consider δ, the enthalpy of mixing (ΔH mix ), and the ideal entropy of mixing of the alloys to develop criteria for the phase stability [1,12]. For example, in the work of Guo et al. [14], the use of δ and ΔH mix as independent variables clearly separates solid-solution phases from amorphous phases but does not necessarily isolate intermetallic compounds from either one of these phases. In addition, in the work of Otto et al. [11], there are atomic substitutions to the solid-solution CrMnFeCoNi alloy that are specifically chosen to follow the Hume-Rothery rules in respect of δ, Δχ, and crystal structure yet do not form a single-phase solid solution. Useful as many of these attempts to encapsulate features of the underlying bonding mechanisms have been, it is clear that a model that can robustly predict, out ...

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Theory of Magnetic and Structural Ordering in Iron

Cited by 474 publications

References 26 publications

Exchange interaction function for spin-lattice coupling in bcc iron

Exchange interaction function for spin-lattice coupling in bcc iron

First-principles elastic constants for the hcp transition metals Fe, Co, and Re at high pressure

Criteria for Predicting the Formation of Single-Phase High-Entropy Alloys

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