Giant magnetocaloric effect in Co2FeAl Heusler alloy nanoparticles

A giant magnetocaloric effect across the ferromagnetic (FM) to paramagnetic (PM) phase transition was observed in chemically synthesized Co2FeAl Heusler alloy nanoparticles with a mean diameter of 16 nm. In our previous report, we observed a significant enhancement in its saturation magnetization (M-s) and Curie temperature (T-c) as compared with the bulk counterpart. Motivated by those results, we aim here to explore the magnetocaloric properties near the T-c. The magnetic entropy change (-Delta S-M) shows a positive anomaly at 1252 K. -Delta S-M increases linearly with the magnetic field, and a large value of similar to 15 J kg(-1) K-1 is detected under a moderate field of 14 kOe. It leads to a net relative cooling power of 89 J kg(-1) for the magnetic field change of 14 kOe. To confirm the nature of magnetic phase transition, a detailed study of its magnetization is performed. The Arrott plot and nature of universal curve conclude that the FM to PM phase transition in the present system is of second-order.

Automated summary

A giant magnetocaloric effect was observed in Co2FeAl Heusler alloy nanoparticles near the ferromagnetic to paramagnetic phase transition, with a positive anomaly in magnetic entropy change and a linear increase with magnetic field. The nature of the phase transition was confirmed to be second-order based on the Arrott plot and universal curve analysis.