  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
have observed a significant enhancement in its saturation magnetization (Ms)
and Curie temperature (Tc) as compared with the bulk counterpart. Motivated
from those results, here, we aim to explore its magnetocaloric properties near
the Tc. The magnetic entropy change shows a positive anomaly at 1252 K.
Magnetic entropy change increases linearly with the magnetic field, and a large
value of ~15 J/Kg-K is detected under a moderate field of 14 kOe. It leads to a
net relative cooling power of 89 J/Kg 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 the universal curve
conclude that FM to PM phase transition in the present system is of
second-order.
