Lattice Dynamics of Fe0.65Ni0.35 Classical Invar

Maliszewski, E.; Bednarski, S.

doi:10.1002/(sici)1521-3951(199902)211:2<621::aid-pssb621>3.3.co;2-x

Cited by 2 publications

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“…However, in these cases, it is far less pronounced and the wave vector is shifted towards the Γ-point. 22,27,29 For Fe 3 Pd one of the transversal acoustic modes in Fig. 5 starts with a negative slope from the Γ-point, which indicates that the system might immediately undergo a long-wavelength distortion without activation barrier.…”

Section: A Phonon Dispersion Relationsmentioning

confidence: 97%

“…rection, which has subsequently been related to any of the three above mentioned anomalies in the past. [21][22][23][24][25][26][27][28][29] Our central aim is thus to investigate the influence of electron-phonon coupling in Fe 3 Ni, Fe 3 Pd and Fe 3 Pt as one of the important mechanisms for structural transformations of Fe-based binary alloys. This complements the experimental information by providing a link between electronic properties and structural distortions, which will help to clarify the microscopic origin of these instabilities.…”

Section: Introductionmentioning

confidence: 99%

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Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys

Gruner,

Adeagbo,

Zayak

et al. 2009

Preprint

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We investigate the binding surface along the Bain path and phonon dispersion relations for the cubic phase of the ferromagnetic binary alloys Fe3X (X = Ni, Pd, Pt) for L12 and D022 ordered phases from first principles by means of density functional theory. The phonon dispersion relations exhibit a softening of the transverse acoustic mode at the M-point in the L12-phase in accordance with experiments for ordered Fe3Pt. This instability can be associated with a rotational movement of the Fe-atoms around the Ni-group element in the neighboring layers and is accompanied by an extensive reconstruction of the Fermi surface. In addition, we find an incomplete softening in [111] direction which is strongest for Fe3Ni. We conclude that besides the valence electron density also the specific Fe-content and the masses of the alloying partners should be considered as parameters for the design of Fe-based functional magentic materials.

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Section: A Phonon Dispersion Relationsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys

Gruner,

Adeagbo,

Zayak

et al. 2009

Preprint

View full text Add to dashboard Cite

show abstract

Section: Introductionunclassified

“…A estrutura cristalina das ligas FeNi em diferentes concentrações também é analisada em muitos casos com ajuda do espalhamento inelástico de nêutrons [16,17]. A dispersão de fônons parece manifestar que o efeito Invar por exemplo, tem relação com o acoplamento forte da rede cristalina e com a convergência das energias das bandas longitudinais e transversais nos limites da primeira zona de Brillouin [17]. Por outro lado, as curvas de magnetização são obtidas em muitas ocasiões com Magnetômetros de Amostras Vibrantes (Vibrating Sample Magnetometer-VSM), que revelam uma isotropia na magnetização a temperatura ambiente, indicando assim que muitas das estruturas bcc que ainda se encontram nas amostras, estão distribuídas aleatoriamente nas subcamadas de FeNi [10].…”

Section: Introductionunclassified

Análise das microestruturas magnéticas em filmes de FeNi

Castro¹

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The present work reports structural and magnetic study of FeNi polycrystalline films on Si substrates. X-ray dispersive energy measurements indicated relative concentrations of 64 % iron and 36 % nickel, which means that the films present Invar concentration, a phenomenon characterized by the decrease of the thermal expansion coefficient of the alloy to very low values. Experimental studies show that this phenomenon is strongly related to the magnetic structure of the alloys, but current theoretical models still cannot fully explain the relation between magnetic and mechanical characteristics of Invar alloys, motivating continued studies on their magnetic properties.In this research, the micromagnetic configuration for three FeNi films in Invar concentration and three different thicknesses (30, 70 and 140 nm) is analyzed according to their thicknesses. Experimental techniques such as SQUID magnetometry and Magnetic Force Microscopy (MFM) were used, as well as computer simulations, to offer more experimental bases that contribute to the understanding of the phenomena present in FeNi36 Invar alloys.Results revealed magnetic inhomogeneities caused by film polycrystallinity. The samples also showed a soft ferromagnetic behavior, with increasing saturation magnetizations and effective anisotropies with increasing thicknesses. Results also showed a great influence of shape anisotropy so that the films are easily magnetized in-plane.Finally, magnetometry measurements were complemented by micromagnetic structure mapping by Magnetic Force Microscopy, the resulting magnetic images were later simulated with the software MUMAX3. The maps revealed domains with local magnetizations parallel to the surface of the films, while the walls have a Bloch-like structure, mainly inside the thicker films. In this way, the anisotropy of the material defines an easy axis of magnetization in the plane of the films, because of the shape anisotropy, which forces the domain walls to distribute in the films, forming irregular zigzag like patterns on the surface.

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Lattice Dynamics of Fe0.65Ni0.35 Classical Invar

Cited by 2 publications

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Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys

Lattice dynamics and structural stability of ordered Fe3Ni, Fe3Pd and Fe3Pt alloys

Análise das microestruturas magnéticas em filmes de FeNi

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