Electronically induced ferromagnetic transitions in Sm5Ge4-type magnetoresponsive phases.

The correlation between magnetic and structural transitions in Gd(5)Si(x)Ge(4-x) hampers the studies of valence electron concentration (VEC) effects on magnetism. Such studies require decoupling of the VEC-driven changes in the magnetic behavior and crystal structure. The designed compounds, Gd(5)GaSb(3) and Gd(5)GaBi(3), adopt the same Sm(5)Ge(4)-type structure as Gd(5)Ge(4) while the VEC increases from 31  e(-)/formula in Gd(5)Ge(4) to 33  e(-)/formula in Gd(5)GaPn(3) (Pn: pnictide atoms). As a result, the antiferromagnetic ground state in Gd(5)Ge(4) is tuned into the ferromagnetic one in Gd(5)GaPn(3). First-principles calculations reveal that the nature of interslab magnetic interactions is changed by introducing extra p electrons into the conduction band, forming a ferromagnetic bridge between the adjacent (∝)(2)[Gd(5)T(4)] slabs.