Probing the order parameter and the c-axis coupling of high-T-c cuprates by penetration depth measurements

We have measured the low-temperature (T) dependence of the anisotropic penetration depth lambda(T) of magnetically aligned powders of HgBa2Can-1CunO2n+2+delta (n = 1 and 3) down to 1.2 K. For both members the T dependence of the in-plane penetration depth