TY - JOUR N2 - We report measurements of the in-plane electrical resistivity rho and thermal conductivity kappa of the intercalated graphite superconductor C6Yb down to temperatures as low as T-c/100. When a field is applied along the c axis, the residual electronic linear term kappa(0)/T evolves in an exponential manner for H-c1 < H < H-c2/2. This activated behavior is compelling evidence for an s-wave order parameter, and is a strong argument against the possible existence of multigap superconductivity. IS - 6 ID - discovery116271 UR - http://dx.doi.org/10.1103/PhysRevLett.98.067003 TI - Bulk evidence for single-gap s-wave superconductivity in the intercalated graphite superconductor C6Yb Y1 - 2007/02/09/ SN - 0031-9007 AV - public KW - THERMAL-CONDUCTIVITY KW - FIELD KW - STATE KW - MODEL PB - AMERICAN PHYSICAL SOC A1 - Sutherland, M A1 - Doiron-Leyraud, N A1 - Taillefer, L A1 - Weller, T A1 - Ellerby, M A1 - Saxena, SS JF - PHYS REV LETT N1 - © 2007 The American Physical Society VL - 98 ER -