Structural and Magnetic Phase Transitions in the Rare-Earth Pnictides

Abstract
The pnictides, a series of rare-earth group-V intermetallic compounds, have the unique property that these cubic materials distort 2-3°K above the Néel point. We are able to explain this unusual behavior by using a model in which the lattice distortions are driven by quadrupole phase transitions which occur at higher temperatures than the magnetic phase transitions.