Fermi Surface Meets Multipoles in Skutterudites

Abstract

In many trivalent filled skutterudites physical properties are characterized by the nesting property of the main Fermi surface and the mutipole orderings. The main conduction band consists of Pnictogen p -orbitals with the symmetry of x y z , and the Fermi surface shows a good nesting property with q =(1, 0, 0). The Coulomb potential up to the sixth order term can couple with such the Pnictogen molcular orbital, as it is the third order term symmetry x y z . Therefore, the orbital multipoles up to rank 6 (hexacontatetrapole moment), originating in 4 f electrons affect the main conduction band in the filled skutterudites. Anti-ferromagnetically ( q =(1, 0, 0)) higher multipole ordering can be assisted by the Fermi surface nesting, to open a gap at the Fermi level, as typically realized in PrRu 4 P 12 . In other many skutterudites, there exist other Fermi surfaces to suppress the anti-ferromagnetically ordering, however multipole moments may change the Fermi surface volumes, because it affects only the main...