Fabrication and characterization of pulsed laser deposition of La1-xCaxMnO3 based heterostructures

Abstract

Excellent quality epitaxial giant magnetoresistive (GMR) perovskite-like manganates oxide of La1-xCaxMnO3 (LCMO) thin films have been fabricated by the Pulsed Laser Deposition (PLD) method. The LCMO films have been successfully grown on single crystal (100)LaAlO3 (LAO) substrates and (100)Silicon (Si) substrates through buffers layers of Titanium Nitride (TiN) and Strontium Titanium Oxide, SrTiO3 (STO). It has been found that the structural quality of the LCMO films improves at higher deposition temperatures and with post deposition annealing. The conductivity and the semiconductor-metal transition temperature (Tc), on the other hand, depend on the crystallinity and the oxygen content of the LCMO films. For deposition on (100)LAO single crystal substrates, a low threshold temperature of 650C for growing epitaxial LCMO films is detected. A magnetoresistance ratio (MR) of -50% at 170K under a B-field of 1.2T is achieved. For LCMO films prepared directly on (100)Si substrates, multi-phase films with Tc less than 77K (liquid nitrogen temperature) are obtained. By introducing buffer layers of TiN and STO, epitaxial LCMO films have been successfully grown on Si substrates. A MR of -50% at 116K under a B-field of 1.2T has been realized in the LCMO/STO/TiN/Si heterostructure.