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Giant Magnetoresistance Effect of the Nanoscale Layered-Perovskite La2.5-xK0.5+xMn2O7 (0 < x < 0.5) |
| ZHONG Wei1;ZHANG Ning2;LIU Xian-Song1;ZHAO Li-Juan1;ZHANG Jian-Rong1;DU You-Wei1 |
| 1National Laboratory of Solid State Microstructures,
Nanjing University, Nanjing 210093
2Key Laboratory of Jiangsu Province for Optic and Electric Techniques, Nanjing Normal University, Nanjing 210024 |
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| Cite this article: |
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ZHONG Wei, ZHANG Ning, LIU Xian-Song et al 2002 Chin. Phys. Lett. 19 857-860 |
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Abstract Nanoscale layered-perovskite La2.5-xK0.5+xMn2O7 (0 < x < 0.5) have been prepared by the modified sol-gel method, and their structures, magnetic and electric properties have been studied. The experimental results show that these materials exhibit paramagnetic-to-ferromagnetic phase transitions at 183, 216, 230, 238, and 249 K for x = 0.05, 0.15, 0.25, 0.35, and 0.45, respectively. For all compositions of La2.5-xK0.5+xMn2O7 investigated here, we have not observed the metal-nonmetal transition phenomena for the whole temperature region (80 - 300 K). The nanoscale samples exhibit highly enhanced magnetoresistance (MR) effects especially at low temperatures (< TC). The MR behaviour can be explained by taking account of the two-dimensionality with anisotropy of the Mn-O networks and nanoscale grain size effect in the layered manganese perovskites.
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| Keywords:
75.30.Sg
82.80.-d
81.05.Mh
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Published: 01 June 2002
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| PACS: |
75.30.Sg
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(Magnetocaloric effect, magnetic cooling)
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82.80.-d
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(Chemical analysis and related physical methods of analysis)
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81.05.Mh
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(Cermets, ceramic and refractory composites)
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