Process parameters and grain boundary effect of La-Sr-Mn-O thin film magnetoresistance

• Main Authors: Yen Bin Haung, 黃彥彬
• Other Authors: In Gann Chen
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/37077568087512249785

碩士 === 國立成功大學 === 材料科學及工程學系 === 89 === The La0.67Sr0.33MnO3-δ (LSMO) film was deposited onto the Si[100]/SiO2 substrate and the single grained YBCO bi-crystal substrate by rf sputtering. The deposition parameters of LSMO were determined by the “Taguchi Method” based on the MR ratio. It is shown that the substrate has the strongest effect, followed by the distance between target and substrate, Ar to oxygen ratio, annealing time and annealing temperature. It is known that YBa2Cu3O6 (YBCO) has a similar crystal structure and lattice parameter to that of LSMO. The lattice mismatch of LSMO/YBCO is 0.46 %, which is smaller than that of 0.90 % for LSMO/STO and 1.2% for LSMO/LAO. The bi-crystal substrate with ~ 15° tilt angle along [001] orientation has been used to study the effect of grain boundary on the MR ratio. It is observed that the inter-granular MR is higher than the intra-granular MR at temperature range of 70-200 K. Typical MR ratio is in the range of 2-4 % at 15K Oe, 100 K. For the LSMO/Bi-xl YBCO samples, it is also observed that crack formed along the grain boundary while annealed at 600°C. It is also observed the formation of Sr rich phase with facet crystalline structure while annealed at 900°C.