Magnetic phase diagram of ordered (Fe1-xMnx)Pt alloys

Menshikov, A.Z.; Antropov, V. P.; Gasnikova, G. P.; Dorofeyev, Yu.A.; Казанцев, В. А.

doi:10.1016/0304-8853(87)90321-0

Cited by 28 publications

(35 citation statements)

References 7 publications

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“…23 show a high degree of L1 0 order at all concentrations, which is consistent with the fact that magnetic ordering occurs well below the structural ordering temperatures in these alloys. Therefore, as a practical simplification we assumed perfect L1 0 ordering and complete disorder of Fe and Mn atoms within their own sublattice.…”

supporting

confidence: 83%

“…Surprisingly, at x = 0.85 we find a first-order transition from the G/C to the F/C phase. The existence of this first-order transition is in excellent agreement with the observed abrupt drop in the mean magnetic moment at this concentration [23]. However, since the F component in the low-temperature Mnrich phase has not been previously identified, the existence of the F/C phase is a prediction that needs to be verified experimentally.…”

supporting

confidence: 83%

“…Note, however, that our calculations are for systems with perfect 3d/5d ordering, while the order parameter in the experimental samples for x = 0.5 and x = 0.6 was 0.79 [23]. concentration range at the Mn-rich end the Fe spin moments are almost perpendicular to the MnPt host in the ground state, while Mn ordering is almost pure C-type.…”

mentioning

confidence: 70%

“…Their structural ordering is of the L1 0 type in the fcc sublattice, with (001) layers of Pt alternating with disordered Fe/Mn layers. Neutron diffraction measurements revealed three collinear and two noncollinear phases [23]. The collinear phases are the ferromagnetic (F) phase at the Fe-rich end, the C-type antiferromagnetic phase at the Mn-rich end, and the G-type antiferromagnetic phase in the middle of the diagram.…”

mentioning

confidence: 99%

“…Experimental lattice constants are used at the concentrations reported in Ref. [23]. At each concentration the calculated total magnetic energy E mag (per Fe/Mn atom, referenced from the paramagnetic state) is fitted to even fourth-order polynomials in the reduced magnetizations m µ = cos θ µ , which are expressed through the fields α ν by the Langevin function.…”

mentioning

confidence: 99%

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Ab InitioConstruction of Magnetic Phase Diagrams in Alloys: The Case ofFe1−xMnxPt

et al. 2015

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A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account for competing interactions and multiple magnetic phases. Application to the Fe 1−x Mn x Pt "magnetic chameleon" system yields the sequence of magnetic phases at T = 0 and the c-T magnetic phase diagram in good agreement with experiment, and a new low-temperature phase is predicted at the Mn-rich end. The importance of non-Heisenberg interactions for the description of the magnetic phase diagram is demonstrated.Magnetic substitutional alloys are often found to excel in applications [1,2], because alloying broadens the parameter space for tuning the desired properties. However, wide tunability, combined with the need to target certain operating temperature ranges, presents a challenge for empirical materials design. Competing magnetic interactions in alloys can produce complicated magnetic phase diagrams (MPD) with multiple magnetic phases [3][4][5][6]. Understanding of the c-T MPD's is therefore essential for the development of advanced magnetic materials. Some MPD's can be computed using the Heisenberg model with empirical or calculated exchange parameters combined with the mean-field approximation (MFA) [7,8] Monte-Carlo simulations [9][10][11][12], or spin-fluctuation theory [13]. However, many systems are not adequately described by the Heisenberg model. In metallic alloys the interaction parameters are sensitive to the electronic structure and population and thereby to the content of the alloy [8,9,11] and to the degree of spin disorder [14]. To avoid the limitations of the Heisenberg model, one can use first-principles spin-dynamics simulations [15] or construct a generalized spin Hamiltonian to map the adiabatic energy surface [16,17] for use in thermodynamic calculations. The energies of disordered spin configurations can also be obtained using the disordered local moment (DLM) model [18,19], where the spin-rotational averaging is done in the coherent potential approximation (CPA). While all these approaches fail in strongly itinerant magnets, they are applicable when the spin moments do not vary by more than 10-20% in different spin configurations. We restrict ourselves to such systems here.First-principles spin-dynamics and the construction of a microscopic generalized spin Hamiltonian are computationally very demanding and unfeasible for most systems of practical interest. We have developed [20] an alternative approach, in which self-consistent DLM and noncollinear CPA calculations are used to construct a Ginzburg-Landau-type totalenergy functional expressed through a small number of relevant magnetic order parameters. Combined with the MFA expression for the magnetic entropy, this method provides the variational free energy. A similar scheme was used to describe the phase transitions in F...

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supporting

confidence: 83%

supporting

confidence: 83%

mentioning

confidence: 70%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Ab InitioConstruction of Magnetic Phase Diagrams in Alloys: The Case ofFe1−xMnxPt

et al. 2015

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Microfabrication of FeMnPt films involving magnetic phase change due to structural transformation caused by ion irradiation

Hasegawa

Kasahara

Sasaki

et al. 2016

Physica Rapid Research Ltrs

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Correlations between crystal structures and magnetic properties of Fe1–xMnx Pt films were studied. The disordered films with x ≥ 0.44 had paramagnetic properties and the ordered films with x ≥ 0.46 had antiferromagnetic properties, viz. a difference of 0.02 in the x ‐value (i.e., 1.0 at%) was found. At x = 0.44 with the ordered structure, the uniaxial magnetocrystalline anisotropy was about 2.1 × 107 erg cm–3. A microfabrication process involving the slight composition difference of 0.02, which results in ferromagnetic–paramagnetic phase change due to the structural transformation caused by ion irradiation, was investigated. Only the area irradiated by Mn ions changed from ferromagnetic to paramagnetic phase. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

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1.4.2.3.2 Cr based concentrated alloys

Shiga¹,

Wada²

3d, 4d and 5d Elements, Alloys and Compounds

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Magnetic phase diagram of ordered (Fe1-xMnx)Pt alloys

Cited by 28 publications

References 7 publications

Ab InitioConstruction of Magnetic Phase Diagrams in Alloys: The Case ofFe1−xMnxPt

Ab InitioConstruction of Magnetic Phase Diagrams in Alloys: The Case ofFe1−xMnxPt

Microfabrication of FeMnPt films involving magnetic phase change due to structural transformation caused by ion irradiation

1.4.2.3.2 Cr based concentrated alloys

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