Doping dependence of phonon and quasiparticle heat transport of pure and Dy-dopedBi2Sr2CaCu2O8+δsingle crystals

摘要: The temperature and magnetic-field (H) dependences of thermal conductivity (\kappa) Bi_2Sr_2CaCu_2O_{8+\delta} (Bi2212) are systematically measured for a broad doping range by using both pure Bi2212 single crystals with tuned oxygen contents Bi_2Sr_2Ca_{1-x}Dy_xCu_2O_{8+\delta} (Dy-Bi2212) different Dy x. In the underdoped samples, quasiparticle (QP) peak below T_c is strongly suppressed, indicating strong QP scattering impurities or defects, whereas phonon enhanced in moderately Dy-doped samples at 10 K observed first time system, which means Dy^{3+} ions not only introduce point defects but also stabilize crystal lattice. subkelvin data show that heat gradually decreases upon lowering hole level. dependence \kappa above 5 mainly due to off vortices. While very weak field \kappa, present an additional "dip"-like term \kappa(H) low field, discussed be related free spins ions. For non-superconducting Dy-Bi2212 x \simeq 0.50, interesting "plateau" feature shows up low-T isotherms characteristic 1 -- 2 T, we discuss possible revlevance magnon excitations.