Anisotropic magnetic penetration depth of grain-aligned HgBa2Ca2Cu3O8+delta

The temperature (T) dependence of the anisotropic magnetic penetration depth lambda( T) of magnetically aligned powders of crystalline HgBa2Ca2Cu3O8+delta is reported. Measurements were performed in the Meissner state using the ac-susceptibility technique. The temperature dependences of the in-plane, lambda(ab)(T), and out-of-plane, lambda(c)(T), penetration depths are markedly different. This is believed to arise from the large anisotropy ratio gamma=[lambda(c)(0)/lambda(ab)(0)]similar or equal to 30. The behavior of lambda(ab)(T) is indicative of d-wave superconductivity while lambda(c)(T) is similar to the behavior expected for a superconductor with intrinsic Josephson coupling between the CuO2 planes. Similar measurements were performed on Ba0.6K0.4BiO3 powders for comparison.