ANISOTROPY OF MULTILAYERED (<font>CU</font>,<font>C</font>)<font>BA</font>2<font>CA</font>3<font>CU</font>4<font>O</font><font>Y</font> SUPERCONDUCTORS STUDIED BY TORQUE MAGNETOMETRY

The magnetic torque of ( Cu , C ) Ba 2 Ca 3 Cu 4 O y ( ( Cu , C )-1234) aligned samples with various carrier concentrations has been measured under a magnetic field of 9 T at 80 K and 90 K. The carrier concentration was determined by Hall effect measurements. From angular dependent torque measurements, the anisotropy ratio γ was estimated using the 3D anisotropic London model. The γvalues decreased from 23 to 10 with an increase in the average Hall number per CuO 2 plane ( n H); however, these samples showed a nearly constant Tc of about 117 K. These results indicate that the anisotropy of ( Cu , C )-1234 strongly reflects the doping levels of the outer planes.