GROWTH AND CHARACTERIZATION OF MAGNETORESISTIVE LA-CA-MN-O FILMS ON SI(100) AND SI(111) SUBSTRATES

In situ grown La-Ca-Mn-O films with (100), (110), and mixed orientatio ns have been prepared by pulsed-laser deposition on YSZ-buffered Si(10 0) and Si(lll) substrates. X-ray diffractometry, magnetoresistance (MR ), and magnetization of these films were measured. The best magnetores istance was observed in the single-phase, epitaxial (110), and this st ructure was grown with the best quality on the YSZ(111)-buffered Si(ll l) substrates. These films showed higher temperatures for the peak res istivity than those in the (100) films. In a magnetic field of 5 T, th e maximum magnetoresistance of 250% and 164% occurred at 195 and 140 K , respectively, in the as-deposited (110) and (100) films. The MR beha vior of these two orientations, as a function of the substrate tempera ture during La-Ca-Mn-O film growth and the orientation of the YSZ buff er layer, is discussed. (C) 1996 American Institute of Physics.