STUDY OF THE ELECTRODYNAMIC RESPONSE OF SmBa2Cu3O7-δ THIN FILMS IN THE MICROWAVE REGION

Abstract

We present some experimental results on the temperature dependence of the surface resistance Rs and magnetic penetration depth λ of thin films of SmBa 2 Cu 3 O 7-δ. The samples, 0.25 μm thick, were grown by a dc sputtering technique on (100) K LaAlO 3 single crystal substrates, with critical temperatures ranging between 87 and 88 K Accurate measurements af the surface impedance Zs were performed down to 4 K by means of a dielectrically loaded cavity operating in the microwave region (20 GHz). Both λ and Rs show a monotonic temperature behavior, with no evidence of low temperature up-turn characteristic of other rare earth based cuprates like GdBa 2 Cu 3 O 7-δ. At low temperatures, we observed am almost linear behavior of λ with a slope of ~ 0.3 nm/K up to 25 K, as expected in a d-wave pairing scenario. The real part of complex conductivity σ1, shows a bump at around 40 K, in agreement with previous reports.