Magnetism, superconductivity and electron correlations in rare earth intermetallics and iron-pnictides

The rare earths (also called lanthanides) are a group of 15 elements in the periodic table, characterized by the gradual filling of fourteen electrons in the 4f-shell. Their intermetallic compounds have proved invaluable in the study of local moment magnetism and the coexistence of magnetism and superconductivity. Some Ce, Yb and 5f-U based systems exhibit strongly correlated electron behavior such as valence fluctuations, Kondo lattices, heavy fermions, unconventional superconductivity, quantum criticality and non-Fermi liquid behavior. The iron-pnictides are a separate class of materials where the parent compounds are mostly spin density wave (SDW) antiferromagnets which upon doping exhibit superconductivity.  In my talk I shall present a brief overview on these materials citing examples both from my work extending over nearly four decades and the literature.