Influence of Ag additions on the superconducting properties of HgBa2CuO4+delta materials - Hole doping and surface barrier effects

A series of superconducting HgBa2CuO4+delta materials, containing Ag-x additions with molar fraction x up to 0.5, has been studied, The processing with Ag at elevated temperatures led to changes in superconducting properties; the properties are consistently interpreted in terms of the superconducting hole density, as obtained from the London penetration depth lambda measured on the same materials, The irreversible magnetic properties are well described in terms of thermally activated tunneling of pancake vortices through a surface barrier.