PENETRATION DEPTH IN MAGNETICALLY ORIENTED, CERAMIC, NI-DOPED AND ZN-DOPED LA2-XSRXCUO4

Understanding the pairing mechanism responsible for superconductivity in the high temperature superconductors remains one of the central iss ues in condensed matter physics. In many experiments it was strongly s uggested that the dominant symmetry of the gap parameter in these mate rials is dx(2)-y(2). To put some more light on this subject we have pe rformed the measurements of the anisotropic penetration depth in La2-x SrxCuO4. The measurements were done for x = 0.08, 0.10, 0.15 and 0.20. We have also doped La1.85Sr0.15CuO4 compound with 0.5 and 1% of Ni an d Zn. The powdered samples, immersed in wax, were magnetically oriente d in field of 10T. The penetration depth was obtained from ac suscepti bility measurements.