  Spherical nanoparticles (NPs) of size 14 nm, made of intermetallic Fe2CoAl
(FCA) Heusler alloy, are synthesized via the co-precipitation and thermal
deoxidization method. X-ray diffraction (XRD) and selected area electron
diffraction (SAED) patterns confirm that the present nanoalloy is crystallized
in A2-disordered cubic Heusler structure. Magnetic field (H) and temperature
(T) dependent magnetization (M) results reveal that the NPs are soft
ferromagnetic (FM) with high saturation magnetization (Ms) and Curie
temperature (Tc). Fe2CoAl nanoalloy does not follow the Slater Pauling (SP)
rule, possibly because of the disorder present in the system. We also
investigate its magnetic phase transition (MPT) and magnetocaloric (MC)
properties. The peak value of the magnetic entropy change vs T curve at a
magnetic field change of 20 kOe corresponds to about 2.65 J/kg-K, and the
observed value of refrigeration capacity (RCP) is as large as 44 J/kg,
suggesting a large heat conversion in magnetic refrigeration cycle. The Arrott
plot and the nature of the universal curve accomplish that the FM to
paramagnetic (PM) phase transition in Fe2CoAl nanoalloy is of second-order. The
present study suggests that the Fe2CoAl nanoscale system is proficient, useful
and a good candidate for the spintronics application and opens up a window for
further research on full-Heusler based magnetic refrigerants.
