Heterogeneous nucleation and heat flux avalanches in La(Fe,Si)$_{13}$ magnetocaloric compounds near the critical point

C. Bennati; L. Gozzelino; E. S. Olivetti; V. Basso

doi:10.1063/1.4971360

paper

Heterogeneous nucleation and heat flux avalanches in La(Fe,Si) $_{13}$ magnetocaloric compounds near the critical point

arXiv:1609.00332 · doi:10.1063/1.4971360

Abstract

The phase transformation kinetics of LaFe $_{11.41}$ Mn $_{0.30}$ Si $_{1.29}$ -H $_{1.65}$ magnetocaloric compound is addressed by low rate calorimetry experiments. Scans at 1 mK/s show that its first order phase transitions are made by multiple heat fllux avalanches. Getting very close to the critical point, the step-like discontinuous behavior associated with avalanches is smoothed out and thermal hysteresis disappears. This result is confirmed by magneto-resistivity measurements and allows to measure accurate values of the zero field hysteresis ( $Δ T_{h y s t}$ = 0.37 K) and of the critical field (H $_{c}$ = 1.19 T). The number and magnitude of heat flux avalanches change with magnetic field, showing the interplay between the intrinsic energy barrier between phases and the microstructural disorder of the sample.

5 pages, 4 figures

Heterogeneous nucleation and heat flux avalanches in La(Fe,Si)13​ magnetocaloric compounds near the critical point

Abstract

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Heterogeneous nucleation and heat flux avalanches in La(Fe,Si) $_{13}$ magnetocaloric compounds near the critical point