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Magnetocaloric materials with first-order phase transition: thermal and magnetic hysteresis in LaFe11.8Si1.2 and Ni2.21Mn0.77Ga1.02 (invited)

Skokov, K. P. and Khovaylo, V. V. and Müller, K.-H. and Moore, J. D. and Liu, J. and Gutfleisch, O. (2012):
Magnetocaloric materials with first-order phase transition: thermal and magnetic hysteresis in LaFe11.8Si1.2 and Ni2.21Mn0.77Ga1.02 (invited).
In: Journal of Applied Physics, AIP Publishing LLC, pp. 07A910, 111, (7), ISSN 00218979, [Online-Edition: http://dx.doi.org/10.1063/1.3670987],
[Article]

Abstract

This is a report on a comparative study of thermal and magnetic hysteresis in LaFe11.8Si1.2 and Ni2.21Mn0.77Ga1.02 polycrystalline samples near their first-order phase transitions by measurements of magnetization and direct measurements of the adiabatic temperature change, ΔTad (H). Based on the obtained M(T) and M(H) dependencies, H-T diagrams were constructed for both alloys and used to explain the ΔTad (H) dependencies. For low thermal hysteresis and a sharp transition in the temperature dependence of magnetization (LaFe11.8Si1.2), the field dependencies of ΔTad (H) are governed by the phase boundary between ferromagnetic and paramagnetic states. For large thermal hysteresis and a broad transition width in temperature(Ni2.21Mn0.77Ga1.02), the phase boundary has little impact on ΔTad (H). It is also shown that, in the phase transition region, ΔTad measured upon the first application of magnetic field (virgin ΔTad (H) leg) can differ from that measured upon subsequent runs of the field. This can lead to an overestimation of the magnetocaloric effect, if only the virgin leg of ΔTad (H) is considered.

Item Type: Article
Erschienen: 2012
Creators: Skokov, K. P. and Khovaylo, V. V. and Müller, K.-H. and Moore, J. D. and Liu, J. and Gutfleisch, O.
Title: Magnetocaloric materials with first-order phase transition: thermal and magnetic hysteresis in LaFe11.8Si1.2 and Ni2.21Mn0.77Ga1.02 (invited)
Language: English
Abstract:

This is a report on a comparative study of thermal and magnetic hysteresis in LaFe11.8Si1.2 and Ni2.21Mn0.77Ga1.02 polycrystalline samples near their first-order phase transitions by measurements of magnetization and direct measurements of the adiabatic temperature change, ΔTad (H). Based on the obtained M(T) and M(H) dependencies, H-T diagrams were constructed for both alloys and used to explain the ΔTad (H) dependencies. For low thermal hysteresis and a sharp transition in the temperature dependence of magnetization (LaFe11.8Si1.2), the field dependencies of ΔTad (H) are governed by the phase boundary between ferromagnetic and paramagnetic states. For large thermal hysteresis and a broad transition width in temperature(Ni2.21Mn0.77Ga1.02), the phase boundary has little impact on ΔTad (H). It is also shown that, in the phase transition region, ΔTad measured upon the first application of magnetic field (virgin ΔTad (H) leg) can differ from that measured upon subsequent runs of the field. This can lead to an overestimation of the magnetocaloric effect, if only the virgin leg of ΔTad (H) is considered.

Journal or Publication Title: Journal of Applied Physics
Volume: 111
Number: 7
Publisher: AIP Publishing LLC
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 26 May 2014 12:04
Official URL: http://dx.doi.org/10.1063/1.3670987
Identification Number: doi:10.1063/1.3670987
Funders: The research leading to these results has received funding from the European Community’s 7th Framework Program under Grant Agreement No. 214864 (SSEEC)., V.V.K. acknowledges support from Development and Creation Program of NUST “MISiS”.
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