On the itinerant magnetism of Mn and its ordered alloys with Fe and Ni

Süss, F.; Krey, U.

doi:10.1016/0304-8853(93)90110-n

Cited by 21 publications

(23 citation statements)

References 17 publications

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“…The onset of a formation of a magnetic moment on the MnIV sites takes place only close to the experimental volume. There are considerable differences compared to some of the previous collinear calculations: In agreement with Antropov et al 27 and Süss and Krey 29 and with our own TB-LMTO calculations, but in disagreement with Sliwko et al 26 and with Asada 28 we find that the MnI atom couples antiferromagnetically to all four MnII atoms surrounding the central atom-Sliwko et al had reported ferromagnetic and antiferromagnetic coupling to groups of two MnII atoms sharing a common edge of the MnII tetrahedron, Asada had assumed a ferromagnetic interaction. We note that if the MnII atoms where divided into two magnetically inequivalent groups, this would result in a further lowering of the magnetic symmetry which is incompatible with the symmetry analysis of Yamada.…”

Section: Collinear Antiferromagnetic ␣-Mnsupporting

confidence: 70%

“…An attempt to determine the noncollinear structure of ␣-Mn was made by Süss and Krey. 29 They used a semiempirical tight-binding method. Their Hamiltonian consists of a paramagnetic part with Slater-Koster parameters for fcc Mn taken from the compilation of Papaconstantopoulous 52 and a Hubbard-type exchange potential, the intra-atomic Coulomb repulsion U between electrons with parallel spin being treated as an adjustable parameter.…”

Section: B State-of-the-art: Theorymentioning

confidence: 99%

“…26 -28 A high-spin state of the Mn atoms at sites I and II, and a marginally magnetic character of those on sites III and IV is predicted in agreement with experiment, but nothing could be said about phase stability and the correlation between the magnetic and geometric structures. On the basis of a semiempirical tight-binding method and a Hubbard-type exchange Hamiltonian, Süss and Krey 29 have calculated both collinear and noncollinear magnetic structures for ␣-Mn. Beyond a critical value of the intra-atomic Coulomb potential U, the collinear calculations converged to high moments on sites I and II, somewhat smaller moments on sites III, and almost nonmagnetic type-IV atoms.…”

Section: Introductionmentioning

confidence: 99%

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Understanding the complex metallic element Mn. I. Crystalline and noncollinear magnetic structure of α-Mn

2003

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Manganese is an element with outstanding structural and magnetic properties. While most metallic elements adopt a simple crystal structure and order magnetically-if at all-in a simple ferromagnetic or antiferromagnetic configuration, the stable phase of manganese at ambient conditions, paramagnetic ␣-Mn, adopts a complex crystal structure with 58 atoms in the cubic cell. At a Néel temperature of T N ϭ95 K, a transition to a complex noncollinear antiferromagnetic phase takes place. The magnetic phase transition is coupled to a tetragonal distortion of the crystalline structure. In this paper we present an ab initio spin-density functional study of the structural and magnetic properties of ␣-Mn. It is shown that the strange properties of Mn arise from conflicting tendencies to simultaneously maximize according to Hund's rule the magnetic spin moment and the bond strength, as expected for a half-filled d band. Short interatomic distances produced by strong bonding tend to quench magnetism. The crystal structure of ␣-Mn is essentially a consequence of these conflicting tendencies-it may be considered as a topologically close-packed intermetallic compound formed by strongly magnetic ͑MnI, MnII͒ and weakly magnetic ͑MnIII͒ or even nearly nonmagnetic ͑MnIV͒ atoms. The noncollinear magnetic structure is due to the fact that the MnIV atoms arranged on triangular faces of the coordination polyhedra are not entirely nonmagnetic-their frustrated antiferromagnetic coupling leads to the formation of a local spin structure reminiscent of the Néel structure of a frustrated triangular antiferromagnet. Consequently, also the other magnetic moments are rotated out of their collinear orientation. The calculated crystalline and magnetic structures are in good agreement with experiment. However, it is suggested that the magnetism leads to a splitting of the crystallographically inequivalent sites into a larger number of magnetic subgroups than deduced from the magnetic neutron diffraction data, but in accordance with NMR experiments. In a companion paper, the properties of the other polymorphs of Mn and their relative stability will be discussed.

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Section: Collinear Antiferromagnetic ␣-Mnsupporting

confidence: 70%

Section: B State-of-the-art: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Understanding the complex metallic element Mn. I. Crystalline and noncollinear magnetic structure of α-Mn

2003

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“…Refs. have extrapolated the magnetic moment per atom to pure Mn equal to 2.3 (±0.1) which was also proved by first principle calculations .…”

Section: Review Of Experimental Datamentioning

confidence: 56%

On the third-generation Calphad databases: An updated description of Mn

Bigdeli

Mao

Selleby

2015

Phys. Status Solidi B

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Aiming for better extrapolations and predictabilities of thermodynamic properties of materials, new thermodynamic models are implemented in the third‐generation Calphad databases. In these models, each term contributing to the Gibbs energy has an explicit physical meaning. Furthermore, descriptions of thermodynamic properties of materials are valid from 0 K up to high temperatures far above the melting point. As a starting point for the development of large self‐consistent third‐generation database, the new models in the present work are applied to the unary manganese system. Taking into account both the calculated first principles results and experimental data, thermodynamic model parameters are evaluated. Thermodynamic properties predicted using this description, agree very well with available data. The calculated properties vary smoothly in the whole temperature range, which is another important improvement compared to the second‐generation databases.

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“…Alternatively, Süss and Krey [38] used an orthogonal TB model with a Hubbard-type exchange Hamiltonian to model antiferromagnetic α-Mn and fcc γ -Mn. They were unable to obtain magnetic moments consistent with experiment unless they used a different value of the Hubbard-U parameter for each of these two structure types nor did they provide a comparison of the predicted relative stabilities.…”

Section: Introductionmentioning

confidence: 99%

Magnetic analytic bond-order potential for modeling the different phases of Mn at zero Kelvin

2014

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It is known that while group VII 4d Tc and 5d Re have hexagonally close-packed (hcp) ground states, 3d Mn adopts a complex χ -phase ground state, exhibiting complex noncollinear magnetic ordering. Density functional theory (DFT) calculations have shown that without magnetism, the χ phase is still the ground state of Mn implying that magnetism and the resultant atomic-size difference between large-and small-moment atoms are not the critical factors, as is commonly believed, in driving the anomalous stability of the χ phase over hcp. Using a canonical tight-binding (TB) model, it is found that for a more than half-filled d band, while harder potentials stabilize close-packed hcp, a softer potential stabilizes the more open χ phase. By analogy with the structural trend from open to close-packed phases down the group IV elements, the anomalous stability of the χ phase in Mn is shown to be due to 3d valent Mn lacking d states in the core which leads to an effectively softer atomic repulsion between the atoms than in 4d Tc and 5d Re. Subsequently, an analytic bond-order potential (BOP) is developed to investigate the structural and magnetic properties of elemental Mn at 0 K. It is derived within BOP theory directly from a new short-ranged orthogonal d-valent TB model of Mn, the parameters of which are fitted to reproduce the DFT binding energy curves of the four experimentally observed phases of Mn, namely, α, β, γ , δ, and -Mn. Not only does the BOP reproduce qualitatively the DFT binding energy curves of the five different structure types, it also predicts the complex collinear antiferromagnetic (AFM) ordering in α-Mn, the ferrimagnetic ordering in β-Mn, and the AFM ordering in γ -, δ-, and -Mn that are found by DFT. A BOP expansion including 14 moments is sufficiently converged to reproduce most of the properties of the TB model with the exception of the elastic shear constants, which require further moments. The current TB model, however, predicts values of the shear moduli and the vacancy formation energies that are approximately a factor of 2 too small, so that a future more realistic model for MD simulations will require these properties to be included from the outset in the fitting database.

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On the itinerant magnetism of Mn and its ordered alloys with Fe and Ni

Cited by 21 publications

References 17 publications

Understanding the complex metallic element Mn. I. Crystalline and noncollinear magnetic structure of α-Mn

Understanding the complex metallic element Mn. I. Crystalline and noncollinear magnetic structure of α-Mn

On the third-generation Calphad databases: An updated description of Mn

Magnetic analytic bond-order potential for modeling the different phases of Mn at zero Kelvin

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