Thin film growth and magnetotransport study of (La,Sr)MnO{sub 3}
- NEC Corp., Tsukuba, Ibaraki (Japan). Fundamental Research Labs.
Thin-film samples of La{sub 1{minus}x}Sr{sub x}MnO{sub 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 (P{sub O{sub 2}}) had the greatest influence on the electrical and magnetic properties. Films grown under a low P{sub O{sub 2}} had a low ferromagnetic transition temperature ({Tc}) 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. The x-ray diffraction analysis and AFM measurements revealed that the films deposited on both MgO (100) and LaAlO{sub 3} (100) were epitaxially grown but contained defect structures. In contrast, grain-free thin films were epitaxially grown on the SrTiO{sub 3} (100) substrates. The surface roughness of films grown on SrTiO{sub 3} was less than 0.3 nm, even for films up to 150 nm thick. Under optimized growth conditions, as-deposited films for x {ge} 0.2 showed a sharp transition in resistivity at {Tc}. Magnetoresistance at far below {Tc} 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{sub 3} substrates.
- OSTI ID:
- 323390
- Report Number(s):
- CONF-971201--; ISBN 1-55899-399-1
- Country of Publication:
- United States
- Language:
- English
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