In:
MRS Proceedings, Springer Science and Business Media LLC, Vol. 494 ( 1997)
Abstract:
Thin-film samples of La 1-x Sr x MnO 3 (x = 0.20 – 0.30) were grown by pulsed-laser deposition using various target compositions, substrate materials, growth temperatures, oxygen partial pressures, and laser-pulse repetition rates. The crystal structure and the transport and magnetic properties of these films were then examined. Of the growth conditions, the oxygen partial pressure (Po 2 ) had the greatest influence on the electrical and magnetic properties. Films grown under a low Po 2 had a low ferromagnetic transition temperature ( T c ) and a wide resistive transition width. None of the heat treatments done after growth improved these films’ quality. The film morphology was significantly affected by the substrate material. Our x-ray diffraction analysis and AFM measurements revealed that the films deposited on both MgO (100) and LaAlO 3 (100) were epitaxially grown but contained defect structures. In contrast, grain-free thin films were epitaxially grown on the SrTiO 3 (100) substrates. The surface roughness of films grown on SrTiO 3 was less than 0.3 nm, even for films up to 150 nm thick. Under optimized growth conditions, as-deposited films for x ≥ 0.2 showed a sharp transition in resistivity at T c . Magnetoresistance at far below T c was as low as that reported for single-crystal sample. Since large magnetoresistance was often observed in polycrystalline samples and believed to be a grain boundary effect, these results indicate the high quality of the films grown on the SrTiO 3 substrates.
Type of Medium:
Online Resource
ISSN:
0272-9172
,
1946-4274
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
1997
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