Return to index
Abstract:
We report the observation
of anomalous Meissner currents in thin films of superconducting YBCO with
oriented internal surfaces introduced by heavy-ion bombardment. High-precision
measurements of the penetration depth (λ) reveal an upturn in the
temperature dependence of λ below T* ≈ 15 K. The magnitude
of the observed effect, its onset temperature and its dependence on the
orientation of the surfaces are in quantitative agreement with the theory
of surface effects in d-wave superconductors. The anomaly is interpreted
to arise from surface currents that are carried by surface-induced Andreev
bound states.
Return to index