Eur. Phys. J. B 5, 847-858 (1998)
https://doi.org/10.1007/s100510050511

Low temperature penetration depth and the effect of quasi-particle scattering measured by millimeter wave transmission in YBa₂Cu₃O_7-δ thin films

¹ Laboratoire de Physique de la Matière Condensée, École Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France
² Brockhouse Institute for Materials Research, McMaster University, Hamilton On. L8S 4M1, Canada
³ Laboratoire de Chimie du Solide et Inorganique Moléculaire, Université de Rennes I, avenue du Général Leclerc, 35042 Rennes Cedex, France

Corresponding author: ^a Louis-Anne.deVaulchier@physique.ens.fr

Received: 22 January 1998
Revised: 18 May 1998
Accepted: 9 June 1998
Published online: 15 October 1998

Abstract

Measurement of the penetration depth as a function of temperature using millimeter wave transmission in the range 130-500 GHz are reported for three (YBCO) laser ablated thin films. Two films, deposited on a substrate (), exhibit a narrow resistive transition (). One has been subsequently irradiated with ions in order to increase the scattering rate of the quasi-particles (). The third film, grown on MgO (), exhibits also a fairly narrow transition () and a high crystalline quality. The experiment provides the absolute value for the penetration depth at low temperature: the derivation from the transmission data and the experimental uncertainty are discussed. We find a zero temperature penetration depth Å, Å and Å, for YBCO-500 Å/ (pristine), YBCO-1300 Å /MgO and YBCO-500 Å / (irradiated) respectively. exhibits a different behavior for the three films. In the pristine sample, shows a clear temperature and frequency dependence, namely the temperature dependence is consistent with a linear variation, whose slope decreases with frequency: this is considered as an evidence for the scattering rate being of the order of the measuring frequency. A two fluids analysis yields . In the two other samples, does not display any frequency dependence, suggesting a significantly larger scattering rate. The temperature dependence is different in these latter samples. It is consistent with a linear variation for the YBCO/MgO sample, not for the YBCO/ irradiated one, which exhibits a T² dependence up to . We have compared our data to the predictions of the d-wave model incorporating resonant scattering and we do not find a satisfactory agreement. However, the large value of in the pristine sample is a puzzle and sheds some doubt on a straightforward comparison with the theory of data from thin films, if considered as dirty d-wave superconductors.