Resistivity and Hall effect in the ab-plane of high Tc HgBa2CaCu2O6+y epitaxial films

By using of high quality HgBa2CaCu2O6+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 TC and the Hall coefficient was studied. 1/RH was found to have T-linear behavior above a crossover temperature T* and a weakened T-dependence below T*. This interesting behavior may be attributed to a pseudo-gap.EIIII/-341-34