Transport properties in single phase superconductor Ba2YCu3O9-δ

Abstract The electrical resistivity and the thermopower are measured on the single phase superconductor Ba 2 YCu 3 O 9 -δ (δ=2.1). The results indicate that the temperature dependences of the resistance and thermopower exhibit typical metallic behaviour, and the sample conducts via electrons at high temperatures. The behaviour of the thermopower can be described with Mott's semi-classical model. The specific heat of electrons in normal state has been estimated 780mJ/K·mole at 200K, i.e. γ =3.9 mJ / K 2 ·mole. Unusual phonon-drag effect is observed above the superconducting transition temperature T c . Below T c , the electrical resistivity and the thermopower all drop to zero corresponding to a superconducting ground state.