Influence of Demagnetization Effect on the Kinetics of the Itinerant Electron Metamagnetic Transition in Magnetic Refrigerant ${\rm La}{({\rm Fe}_{0.88}{\rm Si}_{0.12})}_{13}$

Yako, H.; Fujieda, Shun; Fujita, Akira; Fukamichi, K.

doi:10.1109/tmag.2011.2158522

Cited by 21 publications

(32 citation statements)

References 13 publications

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“…The evolution of the zero-field, thermally induced transition in macroscopic bulk samples has been well described by the Johnson-Mehl-Avrami model of nucleation and growth [12], showing a cooling rate dependence, although more recent work in small fragments studied in vacuum found an athermal rate-independent character to features associated with avalanche-like behaviour in the zero (or very low)-field transition [13]. The temporal evolution of the isothermal transition has also been studied previously [11] and found to evolve from PM to FM over surprisingly long time scales of the order of tens to hundreds of seconds, affected by the demagnetization (shape) of the sample and the magnetic dipole coupling. Previously, we have shown that thermal linkage across the sample plays an equally important role in the temporal evolution of the transition [14].…”

Section: Introductionmentioning

confidence: 76%

“…Field was applied parallel to the axis of the longest sample dimension (i.e. the smallest demagnetizing factor), which yields the maximum magnetic relaxation rate as has been previously shown [11]. For the magnetic relaxation measurements, the field sweep rate to reach the target field was set at 1.7 or 8.3 mT s −1 , as described in the text.…”

Section: Experimental Methodsmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 76%

Section: Experimental Methodsmentioning

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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“…All prototypes to date use magnetic materials that undergo continuous phase transitions in fi eld (such as Gd), [ 2 ] however, in order to reduce the magnetic fi elds required for the applications, there is a move to consider fi rst-order magnetocaloric materials that offer higher performance per Tesla. 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). 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).…”

Section: Introductionmentioning

confidence: 99%

“…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%

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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“…specimen: magnetic-fields direction is parallel (a) and perpendicular (b) to the longitudinal axis of the specimen 22) .…”

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confidence: 99%

Materials Innovations for Magnetic Refrigeration at Room Temperature

Fujita¹

2015

TEION KOGAKU

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Influence of Demagnetization Effect on the Kinetics of the Itinerant Electron Metamagnetic Transition in Magnetic Refrigerant ${\rm La}{({\rm Fe}_{0.88}{\rm Si}_{0.12})}_{13}$

Cited by 21 publications

References 13 publications

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

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

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

Materials Innovations for Magnetic Refrigeration at Room Temperature

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Influence of Demagnetization Effect on the Kinetics of the Itinerant Electron Metamagnetic Transition in Magnetic Refrigerant ${\rm La}{({\rm Fe}_{0.88}{\rm Si}_{0.12})}_{13}$

Cited by 21 publications

References 13 publications

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

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

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

Materials Innovations for Magnetic Refrigeration at Room Temperature

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Product

Resources

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

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

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