Thermopower of double-layered ruthenate Ca3Ru2O7

We measured temperature dependence of in-plane and inter-plane thermopower S-ab and S-c of single crystalline Ca3Ru2O7. The thermopower measurements were carried out by the low-frequency (33 mHz) AC heating method. Large anisotropy between S-ab and S, was observed, and its ratio (S-ab/S-c) is about 15 at 300 K. The sign Of S-ab changes from positive to negative value at the structural transition temperature of 48 K, indicating a reconstruction of Fermi surface. The behavior Of Sab can be explained by the results of the electrical resistivity and Hall coefficient. On the other hand, S-c shows a rather complex behavior. (c) 2006 Elsevier B.V. All rights reserved.