Specific features of spin, charge, and orbital ordering in cobaltites

Complex cobalt oxides known as cobaltites are reviewed, including LnCoO(3)-based perovskite-structured rare-earth cobaltites (where Ln is lanthanum or a lanthanide), quasi-two-dimensional and quasi-one-dimensional cobaltites of the types LnCo(2)O(5+delta), La2CoO4, and Ca3Co2O8, and NaxCoO2 center dot yH(2)O superconducting compounds. Key experimental and theoretical results are presented, with emphasis on the interplay between charge, spin, and orbital degrees of freedom. Two problems of specific relevance to cobaltites - the spin state instability of Co3+ ions in LnCoO(3), and the nature of superconductivity in NaxCoO2 center dot yH(2)O - are also given significant attention.