  Density-functional studies of the electronic structures and exchange
interaction parameters have been performed for a series of ferromagnetic full
Heusler alloys of general formula Co$_2$MnZ (Z = Ga, Si, Ge, Sn), Rh$_2$MnZ (Z
= Ge, Sn, Pb), Ni$_2$MnSn, Cu$_2$MnSn and Pd$_2$MnSn, and the connection
between the electronic spectra and the magnetic interactions have been studied.
Different mechanisms contributing to the exchange coupling are revealed. The
band dependence of the exchange parameters, their dependence on volume and
valence electron concentration have been thoroughly analyzed within the Green
function technique.
