Om. Froehlich et al., PRECISION-MEASUREMENT OF THE AB-PLANE LONDON PENETRATION DEPTH IN HIGH-TEMPERATURE SUPERCONDUCTING THIN-FILMS, Czechoslovak journal of Physics, 46, 1996, pp. 1121-1122
The temperature change of the in-plane penetration depth Delta lambda(
ab)(T) = lambda(ab)(T) - lambda(ab)(O) of HTS thin films was determine
d with an experimental resolution of better than 0.2 Angstrom using a
novel dc-technique based on the measurement of the magnetic field depe
ndence of the critical current of bicrystal grain boundary Josephson j
unctions (GBJs). Over a wide temperature range the data obtained for d
ifferent high temperature superconductors confirm with high accuracy t
he theoretical prediction for a d(x2-y2)-symmetry of the superconducti
ng order parameter in the limit of weak coupling.