Conduction bands in the filled skutterudites

Some filled skutterudite compounds have recently been found to exhibit very interesting properties: a metal–insulator transition (PrRu₄P₁₂), an antiferroquadrupole ordering and heavy-fermion behaviour under magnetic fields (PrFe₄P₁₂) and a new class of heavy-fermion superconductivity (PrOs₄Sb₁₂). Such varied and interesting physical properties are thought to reflect the Fermi surface properties. Band structure calculations have revealed the characteristics of the conduction bands. The main conduction band consisting of p orbitals of pnictogen surrounding the rare-earth ions has a nesting property, and strongly hybridizes with one of 4f electrons. One of the other conduction bands does not have mixing matrix elements with 4f electrons, resulting in the unique band structure in CeOs₄Sb₁₂.