Curie temperature control of La1-xPbxMnO3-y thin film by changing the pulsed laser deposition conditions

The pulsed laser ablation deposition (PLD) method has been used to fabricat e epitaxial films of La1-xPbxMnO3-y (LPMO) oxide and to control Curie tempe rature (T-C) of films by changing the deposition conditions. X-Ray diffract ion indicated growth of epitaxial films with good crystallinity. All films prepared showed metal-insulator phase transition. The respective phase corr esponds to ferromagnetic and paramagnetic one. The transition temperature T -R(max) (nearly equivalent to T-C) decreases from 324 to 246 K with increas ing substrate temperature (T-S) during film deposition. Electron probe micr oanalysis showed that the lead (Pb) concentration in the films decreased (e vaporated) with increasing T-S, indicating that the decrease in T-R(max) is mainly due to the decrease of Pb content in the film. The magnetoresistanc e ratio normalized to the zero-field of a film, whose TRmax is near room te mperature (RT), is 0.45% at magnetic field (H) = 21 kOe at RT. The MR ratio is small unfortunately, however, the present results indicate that the pha se transition temperature can be controlled by changing T-S and epitaxial f ilms with T-R(max) above RT can be prepared by the PLD method. These films are necessary for development of multilayered devices which are composed of ferromagnetic and non-magnetic substances. (C) 2000 Elsevier Science S.A. All rights reserved.