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Temperature Dependence of Anisotropy in Ti and Gd Doped NiMnGa-Based Multifunctional Ferromagnetic Shape Memory Alloys. MATERIALS 2020; 13:ma13132906. [PMID: 32605283 PMCID: PMC7372369 DOI: 10.3390/ma13132906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 12/02/2022]
Abstract
The temperature dependence of magnetocrystalline anisotropy was investigated in detail for the polycrystalline Ni50Mn25Ga25, Ni50Mn25Ga20Ti5 and Ni50Mn25Ga20Gd5 ferromagnetic shape memory alloys in the temperature range of 50–400 K. The effective anisotropy constant was estimated from a series of high field magnetization curves based on the fitting procedure according to the law of approach to magnetic saturation. The low temperature martensitic phase was found to have a significantly higher anisotropy energy in comparison to a high temperature austenitic phase, which was observed through a sudden, distinct drop of anisotropy energy. The calculated values of the effective anisotropy constant were comparable to the results published by other authors. Moreover, the strong influence of chemical composition on the first-order phase transition and the second-order ferromagnetic to the paramagnetic transition was revealed. Finally, the strong coupling between the temperature dependence of the coercive field and the temperature dependence of magnetocrystalline anisotropy was also shown and discussed in the present study.
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Schleicher B, Niemann R, Schwabe S, Hühne R, Schultz L, Nielsch K, Fähler S. Reversible tuning of magnetocaloric Ni-Mn-Ga-Co films on ferroelectric PMN-PT substrates. Sci Rep 2017; 7:14462. [PMID: 29089554 PMCID: PMC5663903 DOI: 10.1038/s41598-017-14525-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022] Open
Abstract
Tuning functional properties of thin caloric films by mechanical stress is currently of high interest. In particular, a controllable magnetisation or transition temperature is desired for improved usability in magnetocaloric devices. Here, we present results of epitaxial magnetocaloric Ni-Mn-Ga-Co thin films on ferroelectric Pb(Mg1/3Nb2/3)0.72Ti0.28O3 (PMN-PT) substrates. Utilizing X-ray diffraction measurements, we demonstrate that the strain induced in the substrate by application of an electric field can be transferred to the thin film, resulting in a change of the lattice parameters. We examined the consequences of this strain on the magnetic properties of the thin film by temperature- and electric field-dependent measurements. We did not observe a change of martensitic transformation temperature but a reversible change of magnetisation within the austenitic state, which we attribute to the intrinsic magnetic instability of this metamagnetic Heusler alloy. We demonstrate an electric field-controlled entropy change of about 31 % of the magnetocaloric effect - without any hysteresis.
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Affiliation(s)
- Benjamin Schleicher
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany.
- TU Dresden, Faculty of Physics, D-01062, Dresden, Germany.
| | - Robert Niemann
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
| | - Stefan Schwabe
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
| | - Ruben Hühne
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
| | - Ludwig Schultz
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
- TU Dresden, Faculty of Physics, D-01062, Dresden, Germany
| | - Kornelius Nielsch
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
- TU Dresden, Faculty of Physics, D-01062, Dresden, Germany
| | - Sebastian Fähler
- IFW Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01069, Dresden, Germany
- TU Dresden, Faculty of Physics, D-01062, Dresden, Germany
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Dubiel Ł, Kuzma M, Stefaniuk I, Wisz G, Wal A. Shape effect in FMR of Ni-Co-Mn-In layers obtained by pulsed laser deposition. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201713302005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Cugini F, Porcari G, Fabbrici S, Albertini F, Solzi M. Influence of the transition width on the magnetocaloric effect across the magnetostructural transition of Heusler alloys. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:20150306. [PMID: 27402934 PMCID: PMC4938065 DOI: 10.1098/rsta.2015.0306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/09/2016] [Indexed: 06/06/2023]
Abstract
We report a complete structural and magneto-thermodynamic characterization of four samples of the Heusler alloy Ni-Co-Mn-Ga-In, characterized by similar compositions, critical temperatures and high inverse magnetocaloric effect across their metamagnetic transformation, but different transition widths. The object of this study is precisely the sharpness of the martensitic transformation, which plays a key role in the effective use of materials and which has its origin in both intrinsic and extrinsic effects. The influence of the transition width on the magnetocaloric properties has been evaluated by exploiting a phenomenological model of the transformation built through geometrical considerations on the entropy versus temperature curves. A clear result is that a large temperature span of the transformation is unfavourable to the magnetocaloric performance of a material, reducing both isothermal entropy change and adiabatic temperature change obtainable in a given magnetic field and increasing the value of the maximum field needed to fully induce the transformation. The model, which is based on standard magnetometric and conventional calorimetric measurements, turns out to be a convenient tool for the determination of the optimum values of transformation temperature span in a trade-off between sheer performance and amplitude of the operating range of a material.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.
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Affiliation(s)
- F Cugini
- Department of Physics and Earth Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma, Italy
| | - G Porcari
- Department of Physics and Earth Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy
| | - S Fabbrici
- IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma, Italy
| | - F Albertini
- IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma, Italy
| | - M Solzi
- Department of Physics and Earth Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy
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Ab Initio and Monte Carlo Approaches For the Magnetocaloric Effect in Co- and In-Doped Ni-Mn-Ga Heusler Alloys. ENTROPY 2014. [DOI: 10.3390/e16094992] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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