Effect of controlled disorder on quasiparticle thermal transport inBi2Sr2CaCu2O8

Abstract

Low-temperature thermal conductivity $\ensuremath{\kappa}$ of optimally doped ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ was studied before and after the introduction of point defects by electron irradiation. The amplitude of the linear component of $\ensuremath{\kappa}$ remains unchanged, confirming the universal nature of heat transport by zero-energy quasiparticles. The induced decrease in the absolute value of $\ensuremath{\kappa}$ at finite temperatures allows us to resolve a nonuniversal term in $\ensuremath{\kappa}$ due to conduction by finite-energy quasiparticles. The magnitude of this term provides an estimate of the quasiparticle lifetime at subkelvin temperatures.