Temperature dependence of the lower critical field in underdoped cuprates

Recently, we have suggested that the underdoped cuprate superconductors should be described by a modified Ginzburg-Landau theory which takes into account their reduced phase stiffness. In the present paper, (i) we calculate physical properties, such as the surface energy, which have not been discussed previously within this scheme, (ii) we propose a unified description of the pseudogap and of the superconducting state of the cuprates, and (iii) by analyzing the temperature dependence of the penetration depth and of the lower critical field we provide additional evidence for the applicability of the modified Ginzburg-Landau theory to underdoped cuprates.