ANISOTROPY OF MULTILAYERED (CU,C)BA2CA3CU4OY SUPERCONDUCTORS STUDIED BY TORQUE MAGNETOMETRY.

The magnetic torque of (Cu,C)Ba2Ca3Cu4Oy( (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 CuO2 plane (nH); 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. [ABSTRACT FROM AUTHOR]