Spin-glass-like behaviour and positive magnetoresistance in oxygen deficient La_2/3Ca_1/3MnO_3-\delta thin films

The magnetism and magnetoresistance (MR) in a series of oxygen-deficient La_2/3Ca_1/3MnO_3-\delta (LCMO) thin films have been investigated. Compared with the films with stoichiometric oxygen concentration, the oxygen-deficient LCMO thin films show a spin-glass-like behaviour at low temperatures, and a positive MR effect above the metal－insulator transition temperature. The mechanism of such unusual phenomena is discussed.