Successive occurrence of ferromagnetic and shape memory properties during crystallization of NiMnGa freestanding films

Rumpf, Holger; Crăciunescu, Corneliu Marius; Modrow, Hartwig; Olimov, K.; Quandt, Eckhard; Wuttig, Manfred

doi:10.1016/j.jmmm.2005.10.001

Cited by 43 publications

(22 citation statements)

References 27 publications

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“…1a with b, one can notice that disordered NiMn-Ga films are more resistant to ordering than Ni-MnSn films, for which the resistivity decreases abruptly at about 520 K due to crystallization. This is in accordance with results of extended X-ray absorption fine structure (EXAFS) [10] measurements, which proved that the successive appearance of ferromagnetic and shape memory properties in annealed Ni-Mn-Ga films are related to the change in chemical ordering and then to an increase in crystalline grain structure, respectively. In the case of our Ni-Mn-Ga(Sn) films, the ferromagnetic ordering was achieved after full thermal cycle since in both films the characteristic "kinks" on ρ(T ) are clearly seen at the Curie temperature T C ≈ 380 K and T C ≈ 320 K, respectively (see Fig.…”

Section: Experimental and Resultssupporting

confidence: 90%

Electric and Magnetic Signatures of Structural and Chemical Ordering of Heusler Alloy Films

et al. 2009

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We present results of in situ temperature measurements of resistivity for some amorphous or partially crystalline Heusler alloy films: Co 2 CrAl, Co 2 MnGa and off-stoichiometric Ni 2 Mn 1+x Sn x , Ni 2 Mn 1−x Ga x that are known to exhibit half-metallic properties and martensitic transformations, respectively. From ρ vs. T characteristics we distinguish various stages of chemical and structural ordering in the films. They appear to be quite distinct in both systems investigated. The resistivity results are compared with magnetic characteristics for Co 2 MnGa with a high Curie temperature.

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Section: Experimental and Resultssupporting

confidence: 90%

Electric and Magnetic Signatures of Structural and Chemical Ordering of Heusler Alloy Films

et al. 2009

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“…6), which is typical for films with highly disordered or poorly crystalline nature. [53][54][55] Such behavior may be attributed to Pauli paramagnetism. Moreover, the loss of ferromagnetic order mainly occurs due to the lack of crystalline order in the film, [43][44][45][46] and this is in good agreement with the XRD result.…”

Section: Hysteresis Loopmentioning

confidence: 99%

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

Kumar

Seenithurai

Raja

et al. 2015

Journal of Elec Materi

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Polycrystalline Ni-Mn-Ga ferromagnetic shape-memory thin films have been deposited on Si (100) substrates using a direct-current magnetron sputtering technique. The microstructure and the temperature dependence of magnetic properties of the films have been investigated by x-ray diffraction, scanning electron microscopy, and thermomagnetic measurements. As-deposited Ni 50.2 Mn 30.6 Ga 19.2 film showed quasi-amorphous structure with paramagnetic nature at room temperature. When annealed at 873 K, the quasi-amorphous film attained crystallinity and possessed L2 1 cubic ordering with high magnetic transition temperature. Saturation magnetization and coercivity values for the annealed film were found to be 220 emu/cm 3 and 70 Oe, respectively, indicating soft ferromagnetic character with low magnetocrystalline anisotropy. The magnetic transitions of the film deposited at 100 W were above room temperature, making this a potential candidate for use in microelectromechanical system devices.

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“…[3][4][5][6]). Studies of shape memory thin films deposited onto various substrates have revealed that they frequently exhibit a two-way shape memory behavior [7][8][9][10][11][12][13]. Observed in these composites reversible bending deformations originate from stress fields which are induced by a lattice mismatch between the film and substrate.…”

Section: Pacs Numbersmentioning

confidence: 99%

Imprinting Bias Stress in Functional Composites

Khovaylo

Lebedev

Zakharov

et al. 2010

Jpn. J. Appl. Phys.

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We propose a simple yet effective method which allows one to attain large reversible shape changes in shape memory bimetallic composites without training procedure. It is based on the conservation of strongly anisotropic martensite microstructure artificially created in the shape memory layer. This procedure results in appearance of stress field when the shape memory layer is transformed to the austenitic state which brings about two-way shape memory effect. Utilization of this method for preparation of TiNi-based composite with a thickness of 60 µm allowed us to achieve 0.9% reversible bending deformation. It is also suggested that the implementation of this method during preparation of piezoelectric or magnetostrictive composites permits to imprint bias stress and thus to improve their characteristics without use of an external load.

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Successive occurrence of ferromagnetic and shape memory properties during crystallization of NiMnGa freestanding films

Cited by 43 publications

References 27 publications

Electric and Magnetic Signatures of Structural and Chemical Ordering of Heusler Alloy Films

Electric and Magnetic Signatures of Structural and Chemical Ordering of Heusler Alloy Films

Structural and Magnetic Properties of Sputter-Deposited Polycrystalline Ni-Mn-Ga Ferromagnetic Shape-Memory Thin Films

Imprinting Bias Stress in Functional Composites

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