Superconductivity and charge-density-wave order in Nao3CoO2-1.3H2O

Na0.3CoO2 1.3H2O progressively changes its properties with ambient temperature ageing from two-gap, layered superconductivity to charge-density-wave order as the number of O vacancies in the layers increase. The charge-density-wave order was theoretically predicted on the basis of band-structure calculations, independently of knowledge of the specific-heat measurements.