  We have employed Gd55Co30NixAl15-x (x = 10, 5 and 0) amorphous microwires as
a model system to unravel the impact of multiple magnetic interactions on the
magnetism and the magnetocaloric behavior in Gd-alloy microwire systems. Our
study shows that in addition to the RKKY ferromagnetic (FM) interaction
(Gd-Gd), antiferromagnetic (AFM) interactions (Gd-Co, Gd-Ni) coexist and
contribute to the magnetic and magnetocaloric response of the system. The
dilution effect of Al element on the FM Gd-Gd interaction is responsible for
the decrease of the Curie temperature (TC), whereas the increase of the
saturation magnetization (MS) is originated from the reduced AFM Gd-Ni
interaction. A thorough analysis of critical exponents suggests that the
presence of the AFM interactions hinders the system to exhibit a long-range FM
order below the TC. Adjusting these interactions is shown to preserve the large
refrigerant capacity (RC) while tuning the TC over a wide temperature range,
which is desirable for active magnetic refrigeration.
