Measurement of the linear thermal expansion α has been carried out for Mn substituted YBa2(Cu1−xMnx)3Oy (0≤x≤2%) using a high resolution dilatometer over the temperature range 10–300 K. Across the superconducting transition, the jump in the coefficient of linear thermal expansion Δα was found to decrease with increasing Mn content. For the pure sample, we observed a negative jump. While a threefold decrease in Δα with x = 0.5% was observed, only slight changes in the oxygen content and transition temperature have been noted, as a function of the Mn concentration. The above observations clearly suggest that the substituent Mn is being incorporated into the superconductors as a whole and not in the form of a local cluster. Further, from the Ehrenfest relations, the pressure dependence of TC (dTC/dP) and the discontinuity in the compressibility, ΔK, are expected to decrease with the Mn concentration.
Authors: Ashok Rao, S Radheshyam, Rajesh Kumar, Sandeep Gupta, C. Meingast, Bhasker Gahtori, S.K. Agarwal, K. Sivakumar, Y-K Kuo
DOI: https://doi.org/10.1088/0953-8984/19/5/056208
Publish Year: 2007
