Capturing first- and second-order behavior in magnetocaloricCoMnSi0.92Ge0.08

Abstract

Here we examine the constituent components that make a magnetocaloric material attractive for application. The field-temperature phase diagram is studied and using calorimetry, the 1 st and 2 nd order components of the magnetic field driven magneto-structural phase transition in We identify 262K as a tricritical point and above this temperature T crit the transition shows only continuous, 2 nd order characteristics. Hall probe imaging that has a five micron pixel resolution is then used to study the striking differences in the spatial evolution of the transition above and belowT crit . We demonstrate that the hysteresis of the transition is linearly related to the magnitude of the latent heat; an observation that has important implications for the use of this and other 1 st order systems for application as magnetic refrigerants.

Origin of Hysteresis in La0.67Ca0.33MnO3

“…We can calculate the entropy change using the magnetization curves or, from the ac calorimetry, and both are shown in figure 5(b). When a system has entropy change contributions from latent heat and a change of heat capacity both components have to be included in order for the total entropy change to equal that calculated from the magnetization curves [33,34]. In figure 5(b) it can be seen that the entropy change calculated from the ac calorimetry agrees with that calculated from magnetisation within the accuracy of our measurement which we estimate to be of the order of 1%.…”

Asymmetry of the latent heat signature in b-axis oriented single crystal Gd5Si2Ge2

“…13,14,15 For many first order systems, the phase transition evolves via the nucleation and growth type mechanism. 16 The energy barrier associated with the first order phase transition can result in nucleation of the FM within a PM matrix, brought about by local strain fields or inhomogeneity that (locally) lowers the energy barrier.…”

Tuning the metamagnetic transition in the (Co, Fe)MnP system for magnetocaloric purposes

“…However, due to the large hysteresis generally observed in these compounds, it is still unclear if their MCE can really be used in a refrigeration cycle ; (iv) Finally, the last family is the silicates derived from CoMnSi. [15][16][17][18] Among the inverse MCE materials, the CoMnSi family appears to be one of the most promising. However, some features limit their MCE performances.…”