Electronic and magnetic properties of Fe3−x Cr x Si ordered alloys from first principles (original) (raw)
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physica status solidi (b), 1980
On the basis of the band structure described in Part I an interpolation scheme is discussed which allows t o make a transformationof the bandstructures of the A2-, B2-, and DO,-type lattices into another ones. For disordered alloys the CPA theory in split-band approximation reveals a d-band narrowing without changing the shape. For partially ordered alloys a combined model is proposed which gives a dependence of the magnetic moments on the proportion of pair probabilities in first end second neighbourhoods, in contradiction to former assumptions, which presume a dependence on the first sphere alone. Auf der Basis der in Teil I besprochenen Bandstrukturen wird ein Interpolationsschema diskutiert, das die Bandstrukturen von A2-, B2-und DO,-Gitter ineinander zu transformieren gestattet. Fur ungeordnete Legierungen ergibt die CPA-Theorie i n Split-band-Naherung ein Schmalerwerden des d-Bandes ohne Formanderung. Fur teilgeordnete Legierungen wird ein kombiniertes Model1 vorgeschlagen, das eine Abhlngigkeit des magnetischen Momentes vom Verhaltnis der Paarwahrscheinlichkeiten in erster und zweiter Sphaire ergibt, im Gegensatz zu fruheren Annshmen, die eine Abhangigkeit allein von der ersten Sphare vorschlagen.
IEEE Transactions on Magnetics, 2005
The influence of order phenomena on the electrical and magnetic properties of a series of Fe-Si alloys is analyzed. Electrical resistivity and hysteresis loop measurements are performed on alloys after different thermal treatments, including annealing and quenching from several temperatures. Mössbauer spectroscopy and differential scanning calorimetry were used to characterize both the type of order existing in the alloys and the order-disorder transition temperature. For the highest quenching temperature, the highest magnetic losses are measured due to internal stresses and disordering induced during quenching. High electrical resistivity is obtained by high-temperature quench only when the Si content was over 10.6 at.%. This occurred due to an order-disorder transition, which reduces the B2 degree of order present in the alloy. On the other hand, disordering appears to be detrimental for the excess losses due to the creation of antiphase domain boundaries.
Magnetic Moments and Hyperfine Parameters of Fe 3- x Cr x Al 0.5 Si 0.5
Journal of the Physical Society of Japan, 2012
Results of X-ray, neutron, magnetization and Mössbauer measurements on polycrystalline samples of Fe 3Àx Cr x-Al 0:5 Si 0:5 (x ¼ 0, 0.125, 0.250, 0.375, and 0.5) alloys, crystallizing in DO 3 type of structure, are presented. X-ray and neutron diffraction confirmed the phase homogeneity of all the samples. The unit cell volume has been proved to be independent of the chromium content. Neutron and Mössbauer measurements disclosed that Cr atoms occupy preferentially B-sites, while D-sites are almost entirely occupied by Al and Si. The total magnetisation as well as the individual magnetic moments FeðA,CÞ , FeðBÞ and CrðB,DÞ have been found to vary linearly with chromium concentration. Influence of local environments on the formation of magnetic moments in Fe 3 Al 0:5 Si 0:5 when chromium is substituted for iron was examined using self-consistent spin-polarized tight-binding linear muffin-tin orbital method (TB-LMTO).
Effect of atomic order on the electrical and magnetic properties of Fe/sub 100-x/Si/sub x/ (6
IEEE Transactions on Magnetics, 2005
The influence of order phenomena on the electrical and magnetic properties of a series of Fe-Si alloys is analyzed. Electrical resistivity and hysteresis loop measurements are performed on alloys after different thermal treatments, including annealing and quenching from several temperatures. Mössbauer spectroscopy and differential scanning calorimetry were used to characterize both the type of order existing in the alloys and the order-disorder transition temperature. For the highest quenching temperature, the highest magnetic losses are measured due to internal stresses and disordering induced during quenching. High electrical resistivity is obtained by high-temperature quench only when the Si content was over 10.6 at.%. This occurred due to an order-disorder transition, which reduces the B2 degree of order present in the alloy. On the other hand, disordering appears to be detrimental for the excess losses due to the creation of antiphase domain boundaries.
Thermodynamic study of the magnetic ordering of Fe3?x Mn x Si alloys
International Journal of Thermophysics, 1991
The compounds Fe 3 xMnxSi exhibit a complex magnetic behavior for 0.6 ~<x~< 1.75 involving ferromagnetic ordering followed by a reordering at lower temperature. Measurements of the thermal expansion ct and the specific heat Cp show only a weak anomaly at the Curie temperature, Tc, whereas a large, relatively sharp peak occurs at the magnetic reordering temperature, T R. Thermal expansion measurements for the Fez 2Mn0.8Si compound made about T R are indicative of long-range ordering that can be suppressed in an applied field of ~0.4T. Magnetization measurements show that low fields, 1-2mT, strongly influence the bulk magnetization. Irreversible magnetization behavior, similar to that in spin-glass systems, is displayed.
Electronic and magnetic structure of ordered fe - ni alloys
Brazilian Journal of Physics, 1993
Self-consistent band-structure calculations were performed for ordered ferromagnetic Fe-Ni alloys, using the Linear Muan-tin Orbital Method. In particular, three compounds are analyzed, namely Ni3Fe, NiFe and NiFes. In order to obtain magnetic and cohesive properties our calculations were ca.rried out at several lattice constants for each compound. The results for the interna1 excess energy show the stability of these alloys, with respect to the pure elemental solids. The dependence of the magnetic moments with the lattice parameter is investigated and calculated for NiFe3. The results show a collapse of its magnetic moment (Invar effect) a.s a function of the sample volume.
Thermodynamic study of the magnetic ordering of Fe 3- x Mn x Si alloy
Int J Thermophys, 1991
The compounds Fe 3 xMnxSi exhibit a complex magnetic behavior for 0.6 ~<x~< 1.75 involving ferromagnetic ordering followed by a reordering at lower temperature. Measurements of the thermal expansion ct and the specific heat Cp show only a weak anomaly at the Curie temperature, Tc, whereas a large, relatively sharp peak occurs at the magnetic reordering temperature, T R. Thermal expansion measurements for the Fez 2Mn0.8Si compound made about T R are indicative of long-range ordering that can be suppressed in an applied field of ~0.4T. Magnetization measurements show that low fields, 1-2mT, strongly influence the bulk magnetization. Irreversible magnetization behavior, similar to that in spin-glass systems, is displayed.
Revista de Chimie, 2017
The paper presents results of theoretical investigations on the structural, magnetic and electronic properties of Fe2-xMnGe:Cux Heusler alloy focusing on the role of iron-copper substitution effects on selected parameters. The calculations were performed on the basis of the density functional theory approach using the plane-wave basis set. The substitution of [Ar]4s1 3d10 copper in place of [Ar]4s2 3d6 iron site was investigated.Among the many interesting properties exhibited by those alloys such as shape memory effect, half-metallicity, magnetoresistance etc. they also demonstrate significant sensitivity to various doping affecting their magnetic characteristics such as magnetic ordering or total magnetic moment, often demonstrating the Slater-Pauling behavior. The Cu substitution caused break of half-metallic character at the same time resulted in increase of magnetization.
Journal of Applied Physics, 2010
First principle calculations using supercell approach and coherent potential approximation ͑CPA͒ are performed to investigate the electronic and magnetic structures of Fe 3−x Mn x Si and Fe 3−y MnSi y alloys, where x , y = 0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.5, 1.75, and 2.25. Using supercell calculations we obtained a metallic behavior for x = 0, 0.25, and 0.5 in Fe 3−x Mn x Si alloys with spin polarizations of 24%, 39%, and 93%, respectively. The behavior starts to be half-metallic at x = 0.75 with a small direct band gap that increases for higher concentrations of Mn. Among the half-metallic systems, only those of L2 1 structure at x = 1 and 2 possess indirect band gaps along ⌫-X symmetry line. The change of Si concentration in Fe 3−y MnSi y structures retrieve the metallic behavior for all concentrations except y = 1.25 that shows a half-metallic behavior with a direct band gap of 0.27 eV. We obtained a good agreement between supercell and CPA calculations for the values of the magnetic moment and the trends of the formation energies, which reveals the validity of the supercell approach in predicting the magnetic structure and the energetics of doped Heusler alloys.
Interesting magnetic properties of Fe $ _ {1-x} $ Co $ _x $ Si alloys
2001
Solid solution between nonmagnetic narrow gap semiconductor FeSi and diamagnetic semi-metal CoSi gives rise to interesting metallic alloys with longrange helical magnetic ordering, for a wide range of intermediate concentration. We report various interesting magnetic properties of these alloys, including low temperature re-entrant spin-glass like behaviour and a novel inverted magnetic hysteresis loop. Role of Dzyaloshinski-Moriya interaction in the magnetic response of these non-centrosymmetric alloys is discussed.