  Magnetism in Ni-Mn-Z (Z = Ga,In,Sn,Sb) Heusler alloys has so far been
predominantly attributed to Rudermann-Kittel-Kasuya-Yoshida type interactions
between Mn atoms. We investigate magnetic interactions in one such alloy,
Ni$_{2}$Mn$_{1.4}$In$_{0.6}$ and attempt to explain the origin of
antiferromagnetic (AFM) interactions that coexist with ferromagnetic ones.
Through the combination of x-ray absorption spectroscopy and x-ray magnetic
circular dichroism (XMCD), we find that Ni plays an important role along with
Mn in the overall magnetism. A significant hybridization that develops between
Mn and Ni orbitals results in a small antiferromagnetic moment at Ni sites. The
shift in the XMCD hysteresis loops in the martensitic phase suggests that
antiferromagnetism results from superexchange like interactions between Mn
atoms mediated by Ni.
