Local magnetic behavior across the first order phase transition in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0003.gif" overflow="scroll"><mml:mi>La</mml:mi><mml:msub><mml:mrow><mml:mo stretchy="false">(</mml:mo><mml:msub><mml:mrow><mml:mi>Fe</mml:mi></mml:mrow><mml:mrow><mml:mn>0.9</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Co</mml:mi></mml:mrow><mml:mrow><mml:mn>0.015</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>Si</mml:mi></mml:mrow><mml:mrow><mml:mn>0

Bennati, Cecilia; Laviano, Francesco; Durin, Gianfranco; Olivetti, E.; Basso, Vittorio; Ghigo, Gianluca; Kuepferling, Michaela

doi:10.1016/j.jmmm.2015.07.105

Cited by 12 publications

(11 citation statements)

References 18 publications

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“…This leads to a T C spreading of around 2.5 K for this single particle. The stepwise transition behavior of MnFePSi is comparable to the temperature dependent magneto-optical imaging of La(Fe,Si) 13 from Bennati et al [21] where a piece of La(Fe,Si) 13 transforms in steps as well. The chemical composition of the five individual MnFePSi particle fragments were estimated by standard EDS, searching for small chemical variations explaining the different T C s of the fragments.…”

Section: Resultssupporting

confidence: 72%

Hysteresis of MnFePSi Spherical Powder Ensembles Studied by Magneto‐Optical Imaging

Funk

Zeilinger

Dötz

et al. 2017

Physica Status Solidi (b)

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Temperature-dependent magneto-optical imaging is applied to study the thermal hysteresis of magnetocaloric MnFePSi spherical powder-packed beds across their magneto-elastic transition. Cooling and heating imaging series are used to analyze the transition of such a complex powder ensemble. The magnetization versus temperature behavior reconstructed from these local measurements shows very good agreement with integral measurements of the magnetization of the whole packed bed. Hence, local magneto-optical imaging measurements represent the ensemble behavior well if the number of measurements is large enough. Furthermore, we analyzed the Curie temperature (T C ) distribution of layers with different T C values and observed that the spread of T C within one layer is larger than the spacing between different layers, leading to a gradual switching behavior of the layer ensemble. Additionally, high resolution light microscopy was applied to observe the transition of individual particles, and correlate it to the local magnetic measurements.

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Section: Resultssupporting

confidence: 72%

Hysteresis of MnFePSi Spherical Powder Ensembles Studied by Magneto‐Optical Imaging

Funk

Zeilinger

Dötz

et al. 2017

Physica Status Solidi (b)

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“…This stress-coupling mechanism has been suggested as an interpretation of experimental in situ X-ray diffraction (XRD) data [71] and from in situ magneto-optical imaging. [72] Recently,f inite-element simulations using am echanically coupled ensemble of 1000 cubes confirmed this type of transition behavior. [57] Theo bserved existence of al ongrange elastic interaction between different parts of as ample led to the speculation that also in magnetocaloric Heusler compounds,t he elastic stress originating from the volume changea tt he MT can influence nucleation patterns,a nd is even proposed to lead to "auto-nucleation" of further nuclei in the strain field of ap receding nucleus.…”

Section: Volume Effectsmentioning

confidence: 88%

“…Therefore, during the transition to the ferromagnetic state, which is connected with an increase in cell volume, the transition is likely to proceed from the corners across the entire surface and then towards the center. This stress‐coupling mechanism has been suggested as an interpretation of experimental in situ X‐ray diffraction (XRD) data and from in situ magneto‐optical imaging . Recently, finite‐element simulations using a mechanically coupled ensemble of 1000 cubes confirmed this type of transition behavior .…”

Section: Stress Couplingmentioning

confidence: 99%

“…Furthermore, the local magnetic fields produced by the sample itself either by ferromagnetic minority phases (e.g., α‐Fe in La(Fe,Si) 13 , see Bennati et al …”

Section: Magnetostatic Couplingmentioning

confidence: 99%

“…Furthermore,t he local magnetic fields produced by the samplei tself either by ferromagnetic minority phases (e.g., a-Fei nL a(Fe,Si) 13 ,s ee Bennati et al [72] )o rg rainst hat have already turned ferromagnetic present magnetostatic stray fields for neighboring sample regions. This considerationw ill also be relevantf or multilayers of magnetocaloric materials (see Section 2.4).…”

Section: Magnetostatic Couplingmentioning

confidence: 99%

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Coupling Phenomena in Magnetocaloric Materials

et al. 2018

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Strong coupling effects in magnetocaloric materials are the key factor to achieve a large magnetic entropy change. Combining insights from experiments and ab initio calculations, we review relevant coupling phenomena, including atomic coupling, stress coupling, and magnetostatic coupling. For the investigations on atomic coupling, we have used Heusler compounds as a flexible model system. Stress coupling occurs in first‐order magnetocaloric materials, which exhibit a structural transformation or volume change together with the magnetic transition. Magnetostatic coupling has been experimentally demonstrated in magnetocaloric particles and fragment ensembles. Based on the achieved insights, we have demonstrated that the materials properties can be tailored to achieve optimized magnetocaloric performance for cooling applications.

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“Two-steps” process in the first-order transformation of giant magnetocaloric materials

et al. 2022

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Local magnetic behavior across the first order phase transition in La(Fe0.9Co0.015Si0

Cited by 12 publications

References 18 publications

Hysteresis of MnFePSi Spherical Powder Ensembles Studied by Magneto‐Optical Imaging

Hysteresis of MnFePSi Spherical Powder Ensembles Studied by Magneto‐Optical Imaging

Coupling Phenomena in Magnetocaloric Materials

“Two-steps” process in the first-order transformation of giant magnetocaloric materials

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