Pressure Dependence of Flux Dynamics in Bi2Sr2CaCu2O8+δ

An important problem in high temperature superconductivity is that of understanding, and ultimately controlling, fluxoid motion. Results are presented in this paper which were obtained using a new technique for measuring the pressure dependence of the transition to superconductivity in a diamond-anvil cell. By monitoring the third harmonic of the acsusceptibility, we observe the onset of irreversible flux motion. This, in turn, enables us to study the effects of pressure on flux motion. Pressure changes the atomic interplanar spacing, and hence the interplanar coupling, without significantly altering the intraplanar superconductivity. Therefore we are able to separate the effects of coupling from other properties that also might affect the flux motion, such as superconducting condensate density, anisotropy, and pinning. Our results directly show the relationship between lattice spacing and the irreversibility line in Bi2Sr2CaCu2O8+δ. [superconductivity; flux dynamics; diamond-anvil cell; ac susceptibility; Bi2Sr2CaCu2O8+δ]