Off-diagonal Seebeck effect and anisotropic thermopower in Bi2Sr2CaCu2O8 thin films

The anisotropy Delta S of the thermopower in thin films of the high-T-c superconductor Bi2Sr2CaCu2O8 is investigated using off-c-axis epitaxial film growth and the off-diagonal Seebeck effect. The measurements represent a new method for the investigation of anisotropic transport properties in solids, taking advantage of the availability of oriented grown crystalline thin films instead of using bulk crystals. First results for the temperature dependence Delta S(T) in Bi2Sr2CaCu2O8 thin films are presented and described within a two-band model. Subjecting the films to heat treatments in different gases at relatively low temperatures, Delta S could reversibly be changed in a wide range.