CRITICAL-CURRENT MEASUREMENTS ON THIN-FILMS OF CERU2

We have deposited thin films of CeRu2 onto SiO2/Si substrates by means of DC magnetron sputtering from a CeRu2 target. Resistivity data show a sharp superconducting transition at a maximum T-c of 5.2 K with a t ypical width of 0.2 K. The critical current in the superconducting mix ed state j(c) shows high values at low fields, indicative of pinning o f flux lines at grain boundaries. However, above reduced fields h = H/ H-c2 approximate to 0.3, j(c) starts to drop, with an anomaly around h similar or equal to 0.7, but without showing a peak near the upper cr itical field. Flux pinning appears to be very weak over an appreciable field range, which is possibly due to the high spin susceptibility of CeRu2.