Transport, thermal and magnetic properties of Ru_1-xSb_xSr₂(Gd_0.7 Ce_0.3)₂Cu₂O_10-d

Electrical resistivity, Hall effect, heat capacity and magnetic susceptibility on Ru_1-xSb_xSr₂(Gd_0.7 Ce_0.3)₂Cu₂O_10-d system were investigated in the temperature range 4-300 K with a magnetic field up to 9 T. The structural analysis was investigated using X-ray diffraction. The resistivity transition temperature decreases from 41 K for x=0.00 to 18 K for x=0.06 Sb. This may be due to a distortion of RuO₆ octahedral, which is responsible of the increase in hole localization. Heat capacity, C(T), shows a jump at the superconducting transition temperature. Hall effect anomalies decrease below magnetic transition T_m, which may be explained within a simple two-band model. The behavior of magnetic susceptibility is caused by antisymetric exchange coupling of the Dzyaloshinsky-Moriya (DM) type between neighboring Ru moments.