Frequency dependent conductivity in YBa2Cu3O7-δ (δ≈0) thin films

Anomalous intensity of the 335 cm−1 phonon in YBa2Cu3O7−δ

Abstract We report results on Raman scattering for the intensity of the 335 cm −1 phonon of A g (pseudo B 1g ) symmetry in thin YBa 2 Cu 3 O 7−δ films on MgO and LaAlO 3 substrates. The intensity of this phonon shows a pronounced increase below 100 K and saturates at low temperatures. We also observe an additional intensity peaking at temperatures close to the superconducting transition T C . This may indicate a structural phase transition in the vicinity of T C .