Effect of hole doping on the London penetration depth in Bi2.15Sr1.85CaCu2O8+δ and Bi2.1Sr1.9Ca0.85Y0.15Cu2O8+δ
We acknowledge funding from the EPSRC (U.K.), for the experimental facilities in Cambridge, and further financial support from The Royal Society, EURYI, and MEXT-CT-2006-039047. W.A. was supported by the Development and Promotion of Science and Technology Talents Project (D.P.S.T.), Thailand.