The thin films synthesis of Ca and Sr perovskites manganites

O. Pană1, C.M. Teodorescu2, D. Macovei2, Al. Darabont3, N. Jumate4, N. Aldea1, M.L. Soran1

1National Institute R&D for Isotopic and Molecular Technologies,71-103 Donath Str. PO Box 700, Cluj-Napoca, Romania
2Natlional Institute R&D of Materials Physics, P.O.Box MG-7 Bucuresti-Magurele, Romania
3 “Babes-Bolyai” Univ. of Cluj, Faculty of Physics, 1 Kogalniceanu Str. Cluj-Napoca, Romania
4Technical University of Cluj-Napoca, Materials Science Department, Cluj-Napoca, Romania

	In the last time appeared a general interest in thin layers preparation domain because were discovered the high temperature supraconductor properties and colossal magnetoresistence of perovskite manganites deposed as thin layers. These materials show great potential applications as actuators, electromagnetic shielding, electronic devices. This fact leaded to improve the techniques for high quality thin films preparation of supraconductors compounds, i.e. sputtering, metal-organics chemical vapors deposition, pulsed laser deposition.
The numerous studies were performed on the La2/3A1/3MnO3 thin layers manganites, where A = Sr or Ca.
	In the present study we report the thin films synthesis and structural, electric and magnetic characterization of the nanostructured La2/3Ca(Sr)1/3MnO3 (LCMO). The manganites were deposed on <100> single crystal substrates, like as MgO and LaAlO3, by both rf sputtering deposition and vacuum vapor deposition methods. 
The LCMO thin films were prepared by rf sputtering from a stoichiometric ceramic target at a power of 1.75 W/cm2. The substrates on which the manganite was deposited were heated at temperatures in the range 650 - 825 °C. As for the vapor deposition method the LCMO material was evaporated by electron bombardment from a Ta crucible hit by a current 20 - 100 mA of electrons accelerated at 1.5 - 2.5 keV. The approximate thickness of the deposited film is measured by a quartz microbalance with typical error on the order of 1 %.
The thin films obtained were characterized by physical methods. A JSM 5600 LV JEOL microscope was used for the SEM and EDX morphological and compositional (surface) characterization. Also the magnetic behavior was evaluated by using a vibrating sample magnetometer equipped with cryostat. Magnetoresistive measurements as a function of temperature were also performed in the temperature range 4 K – 300 K.