Superconducting-state thermodynamic parameters and anisotropy of HgBa2Can-1CunOy by reversible magnetization measurements

Measurements of the reversible magnetization in magnetic fields parallel and perpendicular to the c axis have been performed on magnetically aligned nearly-single-phase crystalline HgBa2Can-1CunOy (n=1, 2, and 3) samples. The basic thermodynamic parameters describing the superconducting state, such as the penetration depth, the coherence length, the lower and upper critical fields, and their anisotropy, were determined. The anisotropy of HgBa2Can-1CunOy was found to increase as the number of the copper oxide layers in the unit-cell increases, although the magnitude of the anisotropy is rather small. Relatively smaller values of the thermodynamic critical field, in comparison with that of YBa2Cu3O7-δ, can cause the lower position of the irreversibility lines determined for the Hg-based superconductors