Superconductivity in the Bi-Sr-Ca(Y,Gd)-Cu-O system: DC magnetic susceptibility and microwave absorption investigations

✍ Scribed by E.V. Sampathkumaran; M.D. Sastry; R.M. Kadam

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 378 KB
• Volume: 159
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(89)90378-x

✦ Synopsis

Microwave absorption and DC magnetic susceptibility measurements are carded out on Bi2Sr2Ca2_xRExCu2Oy (RE=Y, Gd; x = 0, 0.25 and 0.5 ). These studies clearly establish the correlation between conventional DC magnetic susceptibility and changes in microwave reflectivity/absorption as the sample is cooled through the superconducting transition temperature (To). The results indicate that To, as determined by both the methods, initially increases with x, though for higher concentrations of x, superconductivity is suppressed. The Curie-Weiss temperature is found to increase with increasing concentration of Gd. No evidence for the local moment on Cu 2+ is found in the EPR measurements. The EPR of Gd 3+ is observable below 30 K for x=0.5 with a possible evidence for crystal-field interaction. Absence of Gd 3+ EPR signal at higher temperatures, and also for x= 0.25, might imply extra pathways for spin-lattice relaxation.