Two independent magnetic sublattices of Er in the Er5 − x LaxGe3 system

Magnetic measurements of Er_{5 ? x} La_xGe₃ with 1 ? x ? 5 have been done between 4·2 and room temperature. The compounds crystallize in the hexagonal (D8₈) structure (Mn₅Si₃ type) with space group P6₃/mcm. Two independent, ferromagnetic and antiferromagnetic, sublattices of Er exist. The magnetic interaction between the Er atoms in the 6(g) sites is ferromagnetic, while that between the Er atoms in the 4(d) sites is antiferromagnetic. The antiferromagnetic exchange interaction is weak in this system. The first and second La atom substitutes into the 6(g) site, while the third La in Er₂La₃Ge₃ is located in the 4(d) position. The fourth La is probably substituted in such a manner that all the Er atoms are left in the 6(g) sites.