I work on first-principles calculations of DMSs, where I substitute one cation with a 3d transition metal element in a host semiconductor, I plotted the Projected bandstructure and projected density of states (DOSs) of my compound.

I see the paper: J.Phys.:Condens.Matter19(2007)436227

What I have understood is :

• When the broadening of impurity 3d bands around Fermi level (Ef) is partially occupied and situated above p anion states of the host semiconductor, resulting in double exchange interaction.
• The presence of 3d states below the p anion states in the upper part of the valence band (VB) resulting in p-d exchange interaction.
• some compounds have both double and p-d exchange interactions.
• some compounds can have a competition of double and superexchange interaction depending on the position of Ef in top 3d bands.
• In the anti-ferromagnetic superexchange interaction, we need two impurities in the system with anti-parallel aligned and having equal concentrations of c/2, the electronic states with the same spin direction hybridize with each other.

But I am still confused about Superexchange anti-ferromagnetic and ferromagnetic.

Thank you in advance.