Resistivity and hall effect in the ab-plane of high TcHgBa 2CaCu 2O 6+y epitaxial films

Abstract

By using of high quality HgBa 2CaCu 2O 6+y (Hg-1212) epitaxial films the resistivity and the normal state Hall effect in ab-plane have been studied. These properties indicate that Hg deficient Hg-1212 is an under-doped superconductor. In post annealing experiments we found that Hg can diffuse out from and into the films at 350°C depending on the Hg vapor pressure. The Hg deficient films show degraded superconductivity. Through annealing them in Hg atmosphere we recovered completely their superconductivity. Using these Hg-1212 films with different cation vacancy contents the relationship between T c and the Hall coefficient was studied. 1/R H was found to have T-linear behavior above a crossover temperature Y * and a weakended T-dependencebelow T *. This interesting behavior may be attributed to a pseudo-gap.