Doping dependence of the magnetic penetration depth in (Yb1−xCax)(Ba1.6Sr0.4)Cu3O7−δ studied by muon spin rotation

✍ Scribed by C. Bernhard; Ch. Niedermayer; U. Binninger; A. Hofer; J.L. Tallon; G.V.M. Williams; E.J. Ansaldo; J.I. Budnick

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 403 KB
• Volume: 226
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90202-x

✦ Synopsis

We report transverse-field muon spin rotation measurements on the 123 system (Ybo.TCao.3) (Bal.6Sro.4)Cu307_~ for various oxygen and calcium contents. Ca substitution creates additional holes in the CuO2 planes, with increasing Ca content the filling of the CuO chains therefore occurs further in the overdoped regime. By varying the oxygen content in the system with a Ca content of x= 0.3 we investigated within a single system the doping dependence of the low-temperature depolarization rate ao and thus of the magnetic penetration depth from the under-to the heavily overdoped regime. In the heavily overdoped region ao is reduced with Tc despite an increased normal-state carrier concentration, as previously reported for T12Ba2CuO6+~. Around optimal doping (To= T¢,ma~) we observe no "plateau" in ao vs. T¢ like that reported for YBa2Cu307_6, where optimal doping nearly coincides with the filling of the CuO chains. A 'plateau' around optimum doping is however restored in a series of optimally doped samples ( T¢ = T¢,m~) with progressively lower Ca content. These results are discussed in terms of induced superconductivity on well-ordered, nearly oxygen-filled CuO chains.