Characterization of the magnetic interactions of multiphase magnetocaloric materials using first-order reversal curve analysis

Abstract

In order to understand the magnetocaloric response of materials, it is important to analyze the interactions between the different phases present in them. Recent models have analyzed the influence of these interactions on the magnetocaloric response of composites, providing an estimate value of the interaction field that is consistent with experimental results. This paper analyzes to which extent magnetization first-order reversal curve (FORC) method can be used to calculate these interactions. It is shown that the different field ranges that are explored using these techniques (inside the hysteretic region for FORC; close to magnetic saturation for magnetocaloric effect) produce interaction field values that differ in order of magnitude, with FORC being sensitive to the lower values of the interaction field and magnetocaloric analysis accounting for the larger interactions

Light control of the nanoscale phase separation in heteroepitaxial nickelates

“…The behavior is similar to what is observed in other oxides characterized by hysteretic MIT [34][35][36], and explains how a transient temperature spike, as the one induced by the laser pump, can shrink the hysteresis width as observed in Fig. 2.…”

Interpreting first-order reversal curves beyond the Preisach model: An experimental permalloy microarray investigation

“…When investigating single isolated stripes of different width, we find the expected coercivity scaling [43,44] and the FORC peak corresponding to the coercivity of the stripe. Using these simple objects to set up more complicated geometries of alternating stripes, we find that the resulting FORC diagram shows a double peak feature, which can be ascribed to the interaction within the system [29]. Furthermore, the high coercivity peak shifts to higher values due to its interaction with the low coercivity component [27].…”

“…Although FORC provides access to the interactions in a system [24][25][26] the corresponding FORC diagrams can become difficult to interpret as interaction features arise [27][28][29]. In a naive interpretation of FORC each peak corresponds to a specific component in the system of respective coercivity and interaction.…”

Temperature-FORC analysis of a magnetocaloric Heusler alloy using a unified driving force approach (T*FORC)

“…In this case, more conventional field FORC can be performed to gain insight into the magnetic interactions present among different magnetocaloric phases. 13 T-FORC has allowed confirming that the details of the transformation in Heusler alloys depend on the two extensive variables, temperature and field. 14 However, the comparison between the different distributions for different applied fields could only be made qualitatively because the temperature axis has to be arbitrarily shifted for each applied field.…”

“…There have been proposals of new techniques to understand the behavior of FOPT magnetocaloric materials, such as the extension of first order reversal curves (FORCs) 12 to characterize the interactions between phases in multiphase magnetocaloric materials 13 and to fingerprint the details of the hysteresis of the thermomagnetic phase transition. 14 In this latter respect, temperature-FORC (T-FORC) is formally analogous to its more conventional field counterpart, facilitating the study of phase transitions that are driven by temperature.…”