Thermodynamic relevance of nanoscale inhomogeneities in Bi2Sr2CaCu2O8+delta

Abstract

Using finite size scaling we analyze specific heat and London penetration depth data to estimate the spatial extent of the superconducting grains in so called high-quality Bi2Sr2CaCu2O8+delta single crystals. Contrary to the previously investigated type II superconductors, YBa2Cu3O7+delta, MgB2,2H-NbSe2 and Nb77Zr23, where the lower bound for the length scale of the grains ranges from 182 A to 814 A, our analysis uncovers nanoscale superconducting grains. This clarifies the relevance of the spatial variations in the electronic characteristics observed in underdoped Bi2Sr2CaCu2O8+delta with scanning tunnelling microscopy for bulk and thermodynamic properties and establishes their spatial extent.