Effect of Mn substitution on the thermal expansion of EuBa₂Cu₃O_7-δ

In the present communication, effect of Mn substitution on thermal expansion of EuBa₂Cu_3-xMnxO_7-δ has been investigated. Thermal expansion measurements have been carried out using a high resolution dilatometer based on three terminal capacitance method. The present set-up is sensitive enough to detect small changes in linear thermal expansion coefficient, a of less than 10"8 per Kelvin. Results show that the pristine sample exhibits a jump in thermal expansion coefficient around its transition temperature which is a characteristic of a second order phase transition. For the pure sample a jump in a, of the order of 9.5 × 10-8 K-1 has been observed. It is seen that Mn doping reduces the jump in thermal expansion. Using the well-known Ehrenfest relations, both the pressure dependence of Tc, dTc/dP and the discontinuity in compressibility, δK, are determined and are seen to decrease with increase in Mn concentration.