Infinite-layer Ca1-xSrxCuO2 films, where x was 0.66 or 0.9, were grown by means of pulsed laser deposition. They were doped by implanting 70keV O+ ions to a dose of 3 x 1016/cm2. It was found that the resistivity of the films, at temperatures ranging from 4 to 200K, decreased by over 2 orders of magnitude; as compared with as-grown films. Annealing of the as-grown films in an O atmosphere at 500C resulted in only a factor of 2 decrease within this temperature range. A magnetic anomaly which resembled a diamagnetic transition was observed at 85 to 90K in implanted films. It was not observed in as-grown films. A comparison of the properties of implanted films, before and after annealing, suggested that an increased O content alone was not responsible for the observed changes. It was concluded that defect creation that resulted from implantation could also play a significant role.

A.S.Wong, Q.Y.Ma, P.Dosanjh, J.F.Carolan, W.N.Hardy: Journal of Applied Physics, 1995, 78[2], 1382-4