Shape-anisotropic heterogeneous nucleation and magnetic Gibbs-Thomson effect in itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 magnetocaloric compound

Fujita, Akira; Kondo, Tetsuo; Kano, Masayuki; Yako, H.

doi:10.1063/1.4789902

Cited by 19 publications

(19 citation statements)

References 28 publications

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“…One possibility is strain relief: [ 5 ] in polycrystalline samples such as ours, where there is a period of mixed phase the growth itself is known to Adv. This would be consistent with Fujita et al [ 17 ] in which simulations and Seebeck voltage measurements of a rectangular sample suggest that the nucleation of the FM phase for the PM-FM transition occurs at the middle of the sample, whereas the FM-PM transition begins at the ends with respect to the applied fi eld direction. 2015, 5, 1401639 www.MaterialsViews.com www.advenergymat.de wileyonlinelibrary.com not be symmetric, [ 17 ] thus, one would expect any relief from breaking the sample to dominate for the PM-FM case only, where the material increases in volume.…”

Section: Using Sample Shape To Engineer the Magnetic Hysteresissupporting

confidence: 92%

“…Here, we study the magnetization ( M ) dynamics of the transition in a fi rst-order metamagnetic material in response temperature in LaFe 13-x Si x -based materials; [13][14][15][16] generally the M-H loops show "fl aring" as the fi eld rate is increased resulting in increased magnetic hysteresis ( Figure 1 a). Alternatively in the latter case, it has also been suggested that this effect is an intrinsic nucleation and growth process dominated locally by heating/cooling at the phase boundary and the dipole interaction, [ 15,17 ] or by thermal activation over the energy barrier. In the former case once the PM-FM transition has started at some part of the sample, the increase in temperature from the nucleated region heats the surrounding regions and therefore increases their critical fi elds.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Lovell

Pereira

Caplin

et al. 2014

Advanced Energy Materials

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to applied magnetic fi eld ( H ) and demonstrate the importance of sample shape in terms of engineering the magnetic hysteresis of the transition beyond the obvious role of demagnetization. We show that thin samples are required in order to mitigate the extrinsic hysteresis created as the sample approaches adiabaticity in the presence of rapidly changing magnetic fi eld, and to shorten the time required to complete the magnetic transition, thereby allowing an increased refrigeration operation frequency. We also show that unique to fi rst order metamagnetic materials, rectangular rather than square plate geometry is attractive to engineer the onset of paramagnetic (PM) to ferromagnetic (FM) and the reverse transition.First-order magnetocaloric effect (MCE) materials have associated hysteresis in the fi eld-driven metamagnetic transition that leads to energy losses when cycling, [ 2,4 ] and degradation of the magnetocaloric properties has been seen to arise due to the strain effects from the abrupt magnetostructural or magnetovolume changes that such materials exhibit. [ 5 ] Additionally, fi rst-order transitions occur by a nucleation and growth process with a region or period of coexistence of two phases. [ 6 ] When used in commercial-type cooling systems, cycling frequencies in the order of Hz are imperative, [ 7,8 ] with repeated cycling without degradation of the solid magnetocaloric coolant; all of these complicating factors associated with fi rst-order transitions become of overriding importance within a technological context.LaFe 13x Si x compounds with x < 1.6 are a material of choice as they exhibit small hysteresis in their fi rst-order itinerant electron metamagnetic transition between the PM and FM states. [ 9,10 ] This is accompanied by an isotropic volume change of approximately 1% without a change in crystal symmetry, and the Curie temperature, T C , can be easily adjusted by partial substitution on the La or Fe sites or introduction of interstitial hydrogen, allowing T C to approach close to room temperature. [ 11 ] There has been much research into the magnetocaloric properties of this series that are competitive with the benchmark materials, such as Gd, in addition to its excellent temperature-range adaptability. [ 12 ] However, in order to gauge the potential for use as a practical magnetic refrigerant with viable operational frequencies, the importance of time-dependence and fi eld-rate effects of the MCE needs proper examination.Several groups have investigated the apparent dependence of the fi rst-order transition on the rate of change of fi eld and The infl uence of dynamics and sample shape on the magnetic hysteresis in fi rst-order magnetocaloric metamagnetic LaFe 13-x Si x with x = 1.4 is studied. In solid-state magnetic cooling, reducing magnetic and thermal hysteresis is critical for refrigeration cycle effi ciency. From magnetization measurements, it is found that the fast fi eld-rate dependence of the hysteresis can be attributed to extrinsic heating directly related to the thickness o...

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Section: Using Sample Shape To Engineer the Magnetic Hysteresissupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Lovell

Pereira

Caplin

et al. 2014

Advanced Energy Materials

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“…The transient for the lowest temperature shows, however, a peculiar clipping for low magnetic fields, which leads to the flat magnetic field dependence at low magnetic fields seen in Figure . Such an effect can be understood by the scenario schematically sketched in Figure : cooling of the paramagnetic La 1.2 Fe 11.4 Si 1.4 Mn 0.2 sample leads to thermally induced nucleation of the ferromagnetic phase (see Figure a) . Application of a modulated magnetic field leads then due to the MCE to temperature oscillations around the mean sample temperature (which equals the sample holder temperature) as the fraction of the ferromagnetic phase and hence the magnetization changes (see upper transient in Figure b).…”

Section: Resultsmentioning

confidence: 99%

Millisecond Dynamics of the Magnetocaloric Effect in a First‐ and Second‐Order Phase Transition Material

et al. 2018

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The millisecond‐dynamics of the magnetocaloric effect in Gd and La‐Fe‐Si‐Mn, which exhibit first‐ and second‐order phase‐transitions, respectively, are investigated. Direct measurements of the adiabatic temperature change ΔT are obtained from modulation infrared thermometry with field‐cycling frequencies exceeding 1 kHz at amplitudes of up to 45 mT. The peak amplitude of ΔT(T) shows a dependence on sample thickness and decreases with increasing modulation frequency for both materials despite a frequency independent susceptibility of Gd. The adiabatic ΔT depends quadratically on the external field for Gd while La−Fe−Si−Mn shows a peculiar bucket‐shaped curve for temperatures below the peak maximum. A comparative study of non‐caloric samples shows that dissipative heating by eddy currents or magnetic hysteresis does not explain the observed behavior. The transient ΔT(t) instead suggests a mechanism involving strong temperature gradients at the ferromagnetic–paramagnetic boundaries and underlines the importance of further dynamical studies for a fundamental understanding of the magnetocaloric effect in first‐order materials.

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“…We have extracted the latent heat and the inverse heat capacity change in fragments taken from each sample and show that these also decrease to zero as T crit is approached, demonstrating the role played by local thermal linkage in the dynamics of the evolution of the transition. The local nature of the magnetic transition in these materials can be probed also with imaging techniques such as Hall probe imaging [14,25], and can be numerically simulated [26]. We have pointed out the important role of the thermal environment on the observed dynamics in these materials.…”

Section: Resultsmentioning

confidence: 99%

Magnetic relaxation dynamics driven by the first-order character of magnetocaloric La(Fe,Mn,Si) ₁₃

Lovell

Bratko

Caplin

et al. 2016

Phil. Trans. R. Soc. A.

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Here, we study the temporal evolution of the magnetic field-driven paramagnetic to ferromagnetic transition in the La(Fe,Mn,Si) 13 material family. Three compositions are chosen that show varying strengths of the first-order character of the transition, as determined by the relative magnitude of their magnetic hysteresis and temperature separation between the zero-field transition temperature T c and the temperature T crit , where the transition becomes continuous. Systematic variations in the fixed field, isothermal rate of relaxation are observed as a function of temperature and as a function of the degree of first-order character. The relaxation rate is reduced in more weakly first-order compositions and is also reduced as the temperature is increased towards T crit . At temperatures above T crit , the metastability of the transition vanishes along with its associated temporal dynamics.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

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Shape-anisotropic heterogeneous nucleation and magnetic Gibbs-Thomson effect in itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 magnetocaloric compound

Cited by 19 publications

References 28 publications

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Millisecond Dynamics of the Magnetocaloric Effect in a First‐ and Second‐Order Phase Transition Material

Magnetic relaxation dynamics driven by the first-order character of magnetocaloric La(Fe,Mn,Si) ₁₃

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Shape-anisotropic heterogeneous nucleation and magnetic Gibbs-Thomson effect in itinerant-electron metamagnetic transition of La(Fe0.88Si0.12)13 magnetocaloric compound

Cited by 19 publications

References 28 publications

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)13: Reducing Hysteresis

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)13: Reducing Hysteresis

Millisecond Dynamics of the Magnetocaloric Effect in a First‐ and Second‐Order Phase Transition Material

Magnetic relaxation dynamics driven by the first-order character of magnetocaloric La(Fe,Mn,Si) 13

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Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Dynamics of the First‐Order Metamagnetic Transition in Magnetocaloric La(Fe,Si)₁₃: Reducing Hysteresis

Magnetic relaxation dynamics driven by the first-order character of magnetocaloric La(Fe,Mn,Si) ₁₃