Interplay of structural instability and lattice dynamics in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Ni</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mtext>MnAl</mml:mtext></mml:mrow></mml:math>

Mehaddene, T.; Neuhaus, J.; Petry, W.; Hradil, K.; Bourgès, Philippe; Hiess, A.

doi:10.1103/physrevb.78.104110

Cited by 28 publications

(16 citation statements)

References 27 publications

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“…Nevertheless, the phonon density of states computed from measured optical and acoustic phonon branches (Mehaddene et al, 2008) along the symmetry directions of a Ni-Mn-Al crystal exhibits a gap, with the low frequency part arising from the vibration of the heavier atoms, while the contribution of the lighter atoms dominates the uppermost frequency range in contrast to the predictions given by firstprinciples calculations.…”

Section: Phonon Dispersion Curves In the Cubic Austenite Phasecontrasting

confidence: 53%

Magnetic-Field-Induced Effects in Martensitic Heusler-Based Magnetic Shape Memory Alloys

Acet

Mañosa

Planes

2011

Handbook of Magnetic Materials

154

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Section: Phonon Dispersion Curves In the Cubic Austenite Phasecontrasting

confidence: 53%

Magnetic-Field-Induced Effects in Martensitic Heusler-Based Magnetic Shape Memory Alloys

Acet

Mañosa

Planes

2011

Handbook of Magnetic Materials

154

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“…The energy of such anomalous phonon softens with decreasing the temperature. [10][11][12][13][14][15] The temperature dependence of the energy of the anomalous phonon parallels that of the elastic constant CЈ = ͑C 11 − C 12 ͒ / 2, which also softens with decreasing temperature. [16][17][18][19] The softening observed both with neutron scattering and ultrasonic methods is typical for bcc-based solids which undergo martensitic transformations and reflects the dynamical instability of the cubic lattice against shearing of ͕110͖ planes along the ͗110͘ directions.…”

Section: Introductionmentioning

confidence: 85%

Lattice dynamics in magnetic superelastic Ni-Mn-In alloys: Neutron scattering and ultrasonic experiments

et al. 2009

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Neutron scattering and ultrasonic methods have been used to study the lattice dynamics of two single crystals of Ni-Mn-In Heusler alloys close to Ni 50 Mn 34 In 16 magnetic superelastic composition. The paper reports on the experimental determination of the low-lying phonon-dispersion curves and the elastic constants for this alloy system. We found that the frequencies of the TA 2 branch are relatively low and it exhibits a small dip anomaly at a wave number ξ 0 ≈1/3, which softens with decreasing temperature. Associated with the softening of this phonon, we also observed the softening of the shear elastic constant C′=(C 11 −C 12 )/2. Both temperature softenings are typical for bcc-based solids which undergo martensitic transformations and reflect the dynamical instability of the cubic lattice against shearing of {110} planes along ⟨11̅ 0⟩ directions. Additionally, we measured low-lying phonon-dispersion branches and elastic constants in applied magnetic fields aimed to characterize the magnetoelastic coupling. Disciplines Condensed Matter Physics | Metallurgy CommentsThis article is from Physical Review B 79 (2009) Neutron scattering and ultrasonic methods have been used to study the lattice dynamics of two single crystals of Ni-Mn-In Heusler alloys close to Ni 50 Mn 34 In 16 magnetic superelastic composition. The paper reports on the experimental determination of the low-lying phonon-dispersion curves and the elastic constants for this alloy system. We found that the frequencies of the TA 2 branch are relatively low and it exhibits a small dip anomaly at a wave number 0 Ϸ 1 / 3, which softens with decreasing temperature. Associated with the softening of this phonon, we also observed the softening of the shear elastic constant CЈ = ͑C 11 − C 12 ͒ / 2. Both temperature softenings are typical for bcc-based solids which undergo martensitic transformations and reflect the dynamical instability of the cubic lattice against shearing of ͕110͖ planes along ͗110͘ directions. Additionally, we measured low-lying phonon-dispersion branches and elastic constants in applied magnetic fields aimed to characterize the magnetoelastic coupling.

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“…For example, the dynamical instability of the austenite phase prior to the MT commonly gives rise to precursor effects such as the softening of the lowlying transverse TA2-phonon branch [6][7][8][9][10], or the anomalous behavior of the C' shear modulus [11][12][13]. Concerning the origin of the MT it was ascribed to a Jahn-Teller effect [14], since a redistribution of the electronic density of states (DOS) was observed upon the martensitic transformation in Ni2MnGa.…”

Section: Introductionmentioning

confidence: 99%

Determination of the vibrational contribution to the entropy change at the martensitic transformation in Ni–Mn–Sn metamagnetic shape memory alloys: a combined approach of time-of-flight neutron spectroscopy andab initiocalculations

Recarte

Zbiri

Jiménez‐Ruiz

et al. 2016

J. Phys.: Condens. Matter

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The different contributions to the entropy change linked to the austenite-martensitic transition in a Ni-Mn-Sn metamagnetic shape memory alloy have been determined by combining different experimental techniques. The vibrational contribution has been inferred from the vibrational density of states of both the martensitic and austenite phases. This has been accomplished by combining time-of-flight neutron scattering measurements and ab-initio calculations. Further, the electronic part of the entropy change has also been calculated. Since the martensitic transformation takes place between two paramagnetic phases, the magnetic contribution can be neglected and the entropy change can be reduced to the sum of two terms: vibrational and electronic. The obtained value of the vibrational contribution (−36 ± 5 J kg −1 K −1 ) nearly provides the total entropy change measured by calorimetry (−41 ± 3 J kg −1 K −1 ), the difference being the electronic contribution within the experimental error.3

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Interplay of structural instability and lattice dynamics inNi2MnAl

Cited by 28 publications

References 27 publications

Magnetic-Field-Induced Effects in Martensitic Heusler-Based Magnetic Shape Memory Alloys

Magnetic-Field-Induced Effects in Martensitic Heusler-Based Magnetic Shape Memory Alloys

Lattice dynamics in magnetic superelastic Ni-Mn-In alloys: Neutron scattering and ultrasonic experiments

Determination of the vibrational contribution to the entropy change at the martensitic transformation in Ni–Mn–Sn metamagnetic shape memory alloys: a combined approach of time-of-flight neutron spectroscopy andab initiocalculations

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