A First‐Principles Investigation of the Compositional Dependent Properties of Magnetic Shape Memory Heusler Alloys

Siewert, Mario; Gruner, Markus E.; Hucht, Alfred; Herper, Heike C.; Dannenberg, Antje; Chakrabarti, Aparna; Singh, Navdeep; Arróyave, Raymundo; Entel, P.

doi:10.1002/adem.201200063

Cited by 60 publications

(37 citation statements)

References 72 publications

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“…In Fe-Rh there is still some controversy on whether the major contribution to the entropy change arises from conduction electrons or from magnetic moments. While x-ray photoemission 47 . Therefore, while the transition in Fe-Rh is magnetically driven, with magnetization being the primary ferroic property, in magnetic shape memory alloys the martensitic transition is vibrationally driven, with a shear strain as a primary ferroic property.…”

Section: Discussionmentioning

confidence: 99%

Barocaloric and magnetocaloric effects inFe49Rh51

et al. 2014

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We report on calorimetry under applied hydrostatic pressure and magnetic field at the antiferromagnetic (AFM)-ferromagnetic (FM) transition of Fe 49 Rh 51 . Results demonstrate the existence of a giant barocaloric effect in this alloy, a new functional property that adds to the magnetocaloric and elastocaloric effects previously reported for this alloy. All caloric effects originate from the AFM/FM transition which encompasses changes in volume, magnetization and entropy.The strong sensitivity of the transition temperatures to both hydrostatic pressure and magnetic field confers to this alloy outstanding values for the barocaloric and magnetocaloric strengths (|∆S|/∆p ∼ 12 J kg −1 K −1 kbar −1 and |∆S|/µ 0 ∆H ∼ 12 J kg −1 K −1 T −1 ). Both barocaloric and magnetocaloric effects have been found to be reproducible upon pressure and magnetic field cycling. Such a good reproducibility and the large caloric strengths make Fe-Rh alloys particularly appealing for solid-state cooling technologies at weak external stimuli.

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Section: Discussionmentioning

confidence: 99%

Barocaloric and magnetocaloric effects inFe49Rh51

et al. 2014

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“…Since then "ferromagnetic shape memory" materials, characterized by the coexistence of martensitic transformation and magnetic order, have become an emerging class of materials where new properties and potential fields of applications have constantly come to light [2]. The strong coupling between magnetic and structural degrees of freedom is at the basis of their extraordinary phenomenology that offers also exciting matter for basic investigation [3]. While MIR up to 12% in the martensitic phase due to a magnetostructural coupling on the mesoscopic scale was mainly found in NiMnGa alloys [4,5], giant properties changes obtained by inducing structural transition by external fields (i.e., magnetic field, pressure, stress) were mainly shown in off-stoichiometric Mn-rich Heuslers composed of different IIIA-VA elements (i.e., In, Sn, Sb) [6].…”

Section: Introductionmentioning

confidence: 99%

Co and In Doped Ni-Mn-Ga Magnetic Shape Memory Alloys: A Thorough Structural, Magnetic and Magnetocaloric Study

Fabbrici

Porcari

Cugini

et al. 2014

Entropy

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Abstract:In Ni-Mn-Ga ferromagnetic shape memory alloys, Co-doping plays a major role in determining a peculiar phase diagram where, besides a change in the critical temperatures, a change of number, order and nature of phase transitions (e.g., from ferromagnetic to paramagnetic or from paramagnetic to ferromagnetic, on heating) can be obtained, together with a change in the giant magnetocaloric effect from direct to inverse. Here we present a thorough study of the intrinsic magnetic and structural properties, including their dependence on hydrostatic pressure, that are at the basis of the multifunctional behavior of Co and In-doped alloys. We study in depth their magnetocaloric properties, taking advantage of complementary calorimetric and magnetic techniques, and show that if a proper measurement protocol is adopted they all merge to the same values, even in case of first order transitions. A simplified model for the estimation of the adiabatic temperature change that relies only on indirect measurements is OPEN ACCESSEntropy 2014, 16 2205 proposed, allowing for the quick and reliable evaluation of the magnetocaloric potentiality of new materials starting from readily available magnetic measurements.

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“…Here, the structural change is important and involves a tetragonal or orthorhombic distortion or a monoclinic modulated structure as well as a small change of volume. This structural change goes hand in hand with a reconstruction of the Fermi surface [23,24]. In addition, the disorder and associated changes of Mn-Mn distances between the Mn atoms in X 50 Y 25 þ x Z 25 À x (X ¼ Ni, Co, Y ¼Mn, and Z ¼Ga, In, Sn and x¼ excess Mn) result in strong antiferromagnetic exchange interactions between Mn Y -Mn Z atoms.…”

Section: Origin Of Metamagnetic Behaviormentioning

confidence: 96%

“…There is renewed interest in metamagnetism of antiferromagnetic metals [25]. In particular, the interest is in the appearance of metamagnetism and magnetostructural transition in magnetic Heusler alloys since this may be considered as the origin of 'massive magnetic-field induced structural transformation' which leads to giant inverse MCE across the magnetostructural transition [17,24,26,27]. The related aspects of magnetostructural transition and kinetic arrest phenomena which lead to strain glasses as well as appearance of magnetic cluster-spin glasses at low temperatures of the phase diagram of magnetic Heusler alloys are beyond the scope of this paper and will not further be discussed here.…”

Section: Origin Of Metamagnetic Behaviormentioning

confidence: 99%