Effects of the pseudo-gap on the field-induced kinetic energy density of Bi2Sr2CaCu2O8+δ single crystals

We report on magnetization experiments from which we obtain the field-induced kinetic energy density, Ek, in the superconducting phase of several Bi2Sr2CaCu2O8+δ single crystal samples. The kinetic energy magnitude changes according to the characteristic reduction of the single-electron density of states produced by the pseudogap in the underdoped limit. Moreover, a remarkable peak of Ek occurring at the specific holes density p∼0.18 is related to a van Hove singularity due to the pseudogap closure. We also extracted the superfluid density, ρs. We conclude that Ek and ρs are related to the pseudogap energy scale. This result is understood as an evidence of the coexistence between superconductivity and the pseudogap phenomenon in the Bi2Sr2CaCu2O8+δ cuprate compound.