CO-DOPED BI2SR2CACU2OX - ANDERSON LOCALIZATION AND SUPERCONDUCTIVITY

Cobalt-doping of Bi2Sr2CaCu2Ox beyond a critical level of 1.5-1.6 at % produces both a large decrease in the superconducting transition crit ical temperature and all of the classic symptoms of Anderson localizat ion. These include: a negative slope of the ab-plane resistivity vs te mperature, no dispersing states near the Fermi level and a decrease of the photoemission signal in the same region. The correlation between Anderson localization and high-temperature superconductivity at low do ping levels supports a non-local interaction for the paring mechanism, such as antiferromagnetic spin fluctuations.