Electronic inhomogeneity and breakdown of the universal thermal conductivity of cuprate superconductors.
We report systematic, high-precision measurements of the low-T (down to 70 mK) thermal conductivity kappa of YBa2Cu3O(y), La(2-x)Sr(x)CuO4, and Bi2Sr2CaCu2O(8+delta). Careful examinations of the Zn- and hole-doping dependences of the residual thermal conductivity kappa0/T, as well as the in-plane anisotropy of kappa0/T in Bi2Sr2CaCu2O(8+delta), indicate a breakdown of the universal thermal conductivity, a notable theoretical prediction for d-wave superconductors. Our results point to an important role of electronic inhomogeneities, which are not considered in the standard perturbation theory for thermal conductivity, in the underdoped to optimally doped regime.
Central Research Institute of Electric Power Industry, Komae, Tokyo 201-8511, Japan.
X F
XF
Sun
S
S
Ono
Yasushi
Y
Abe
Seiki
S
Komiya
Kouji
K
Segawa
Yoichi
Y
Ando