Temperature dependent low-field measurements of the magnetocaloric Δ<i>T</i> with sub-mK resolution in small volume and thin film samples

Döntgen, Jago; Rudolph, J.; Gottschall, Tino; Gutfleisch, Oliver; Salomon, Steffen; Ludwig, Alfred; Hägele, D.

doi:10.1063/1.4906426

Cited by 23 publications

(16 citation statements)

References 21 publications

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“…The geometric demagnetization factor N can be approximately calculated for a right rectangular prism and can be found in Table . Only for the largest H ext , a deviation from the quadratic rule is found when M starts to saturate and is no longer proportional to H i …”

Section: Resultsmentioning

confidence: 99%

“…The magnetocaloric effect was studied by the recently developed modulation infrared thermometry (MIRT) technique …”

Section: Methodsmentioning

confidence: 99%

“…In addition, temperature‐dependent MCE measurements were performed by slowly sweeping the sample temperature while measuring only the 2nd harmonic of the detector signal as the leading contribution (the MCE depends only on the absolute value of the magnetic field). A more in depth description of the setup and experimental procedures was previously published …”

Section: Methodsmentioning

confidence: 99%

“…Reliable methods for the determination of magnetocaloric key parameters such as the adiabatic temperature change Δ T are a prerequisite for the identification of suitable materials. The recently developed method of modulation infrared thermometry allows the direct determination of Δ T even for low‐volume samples, thus avoiding the limitations of calorimetric measurements or indirect approaches such as isothermal magnetization measurements. Going beyond the mere determination of the magnetocaloric parameters, the dynamics of the MCE has attracted growing interest .…”

Section: Introductionmentioning

confidence: 99%

“…Both magnetocooling device concepts and magnetocaloric material classes are intensively explored. [2,3] Reliable methods for the determinationo fm agnetocaloric key parameters such as the adiabatic temperature change DT are ap rerequisite for the identification of suitable materials.T he recently developed method of modulation infrared thermometry [4,5] allows the direct determinationo fDT even for low-volume samples,t hus avoiding the limitations of calorimetric measurements or indirect approaches such as isothermal magnetization measurements.G oing beyond the mere determination of the magnetocaloric parameters,t he dynamics of the MCE has attracted growingi nterest. [6][7][8][9][10] Thei nfluence of,f or example,f ield-sweep rate or field-cycling frequency on the magnetocaloric effect is not only of fundamental interest, but also relevant for the designo fm agnetocooling devices.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

“…The magnetocaloric effect was studied by the recently developed modulation infrared thermometry (MIRT) technique …”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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Experimental Evaluation of 3D Heat Flow Using Magneto‐Thermoelectric Effects in a Ferromagnetic Nanowire

Kamruzzaman

Ohnishi

et al. 2022

Physica Rapid Research Ltrs

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Herein, a systematic measurement of magneto‐thermoelectric voltage induced in a ferromagnetic permalloy nanowire under the operation of a laterally configured nanospintronic device is performed. It is shown that the angular dependences of the magneto‐thermoelectric signals with various probe configurations can be quantitatively understood by the combination of the magneto‐Seebeck and anomalous Nernst effects. Surprisingly, the contribution of the transverse magneto‐Seebeck effect becomes significant in a certain probe configuration, indicating the importance of the transverse heat flow. These results allow us to analyze the 3D distribution of the heat flow inside the permalloy nanowire. The present demonstration indicates that the magneto‐thermoelectric effect is a powerful and reliable tool for analyzing the heat distribution in nanostructured devices.

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Giant Magnetocaloric Effect in Magnets Down to the Monolayer Limit

Yin

Gong

et al. 2023

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Abstract2D magnets can potentially revolutionize information technology, but their potential application to cooling technology and magnetocaloric effect (MCE) in a material down to the monolayer limit remain unexplored. Herein, it is revealed through multiscale calculations the existence of giant MCE and its strain tunability in monolayer magnets such as CrX3 (X = F, Cl, Br, I), CrAX (A = O, S, Se; X = F, Cl, Br, I), and Fe3GeTe2. The maximum adiabatic temperature change (), maximum isothermal magnetic entropy change, and specific cooling power in monolayer CrF3 are found as high as 11 K, 35 µJ m−2 K−1, and 3.5 nW cm−2 under a magnetic field of 5 T, respectively. A 2% biaxial and 5% a‐axis uniaxial compressive strain can remarkably increase of CrCl3 and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is found that large net magnetic moment per unit area favors improved MCE. These findings advocate the giant‐MCE monolayer magnets, opening new opportunities for magnetic cooling at nanoscale.

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Temperature dependent low-field measurements of the magnetocaloric ΔT with sub-mK resolution in small volume and thin film samples

Cited by 23 publications

References 21 publications

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

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

Experimental Evaluation of 3D Heat Flow Using Magneto‐Thermoelectric Effects in a Ferromagnetic Nanowire

Giant Magnetocaloric Effect in Magnets Down to the Monolayer Limit

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