Understanding the Phase Transitions of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Ni</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mi>MnGa</mml:mi></mml:math>Magnetic Shape Memory System from First Principles

Uijttewaal, M.; Hickel, Tilmann; Neugebauer, Jörg; Gruner, Markus E.; Entel, P.

doi:10.1103/physrevlett.102.035702

Cited by 150 publications

(109 citation statements)

References 30 publications

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“…By contrast, our permeability measurements showed a small dip at the premartensitic transition, and the linear strain and permeability exhibited clear variations for the x = 0.15 alloy. Uijttewaal et al [43] state that the contributions of both magnons and phonons to the free energy of premartensite and austenite only "slightly differ" and that the existence of the premartensitic transition results from a delicate interplay between the vibrational and magnetic excitation mechanisms. We considered that the clear variation in the linear strain indicates lattice deformation and a softening of the lattice.…”

Section: Resultsmentioning

confidence: 99%

Magnetostriction of Ni2Mn1−xCrxGa Heusler Alloys

Sakon

Fujimoto

Kanomata

et al. 2017

Metals

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Among the functionalities of magnetic Heusler alloys, magnetostriction is attracting considerable attention. The alloy Ni 2 MnGa has a premartensite phase, which is a precursor state to the martensitic transition. Some researchers have observed magnetostriction in this alloy in the premartensite phase. We performed magnetostriction studies on the premartensite phase of related Cr-substituted Ni 2 Mn 1−x Cr x Ga alloys and measured the thermal strain, permeability, magnetisation, and magnetostriction of polycrystals. Our thermal expansion measurements show an anomaly that indicates the occurrence of lattice deformation below the premartensitic transition temperature T P . Our permeability measurements also showed an anomaly at the premartensitic transition. From our magnetisation results, we obtained the magnetic-anisotropy constant K 1 . In the martensite phase, we found that the magnetic-anisotropy constant of the x = 0.00 alloy is larger than that of the x = 0.15 alloy. At 0.24 MA/m, we obtained a magnetostriction of −120 ppm for the x = 0.15 alloy. Magnetostriction in the premartensite phase is larger than that in the austenite and martensite phases at low magnetic-field strength, thus indicating that it is related to lattice softening in the premartensite phase. The e/a is proportional to the magnetostriction and T P , which indicates that the electron energy, the magnetostriction, and the T p are correlative each other.

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Section: Resultsmentioning

confidence: 99%

Magnetostriction of Ni2Mn1−xCrxGa Heusler Alloys

Sakon

Fujimoto

Kanomata

et al. 2017

Metals

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“…3 In contrast, an accurate and complete ab initio description of temperature-driven transitions is still in its infancy even for simple elementary metals. Corresponding studies are rare 4,5 and a reliable extension to complex materials will only be feasible upon major advances in the field.…”

Section: Pacs Numbersmentioning

confidence: 99%

Temperature-driven phase transitions from first principles including all relevant excitations: The fcc-to-bcc transition in Ca

et al. 2011

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“…Magnetism plays a key role in the stability of the austenite phase towards further transitions, demonstrating that a strong magneto-elastic interaction is necessary for the induction of the intermediate phase in Ni50Mn25Ga25 [24][25][26]. Additionally, the increase of the atomic order degree stabilizes the structural phase exhibiting a higher magnetic moment, as a result of the effect of the magnetic exchange coupling variations on the free energy difference between the austenite and martensite phases [27].…”

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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Understanding the Phase Transitions of theNi2MnGaMagnetic Shape Memory System from First Principles

Cited by 150 publications

References 30 publications

Magnetostriction of Ni2Mn1−xCrxGa Heusler Alloys

Magnetostriction of Ni2Mn1−xCrxGa Heusler Alloys

Temperature-driven phase transitions from first principles including all relevant excitations: The fcc-to-bcc transition in Ca

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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