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摘要
The ferromagnetic order in La0.67Ca0.33MnO3 (LCMO) films has been tuned both by vacuum annealing and substrate-induced strain. And the relation between magnetization (M) and resistivity (rho) was investigated as a function of Curie temperature (T-c). With decreasing T-c, the magnetoresistance (MR) increases, reflecting the stronger magnetism-resistivity correlation at lower T-c. It is interestingly found that the relation between rho and M maintains a form of rho = rho(0)exp(-M/alpha) for temperature near and slightly below T-c despite the fact that T-c is tuned over a wide temperature range, which reveals the dominant role of magnetic polaron on the transport properties. More interestingly, by exploring the rho-M dependence of LCMO combined with the results of La0.67Sr0.33Mn1-xFexO3, it is found that the coefficient alpha decreases universally with the reduction T-c. This implies the tunability of the magnetic polaron could be an important reason for the stronger magnetism-resistivity correlation at lower T-c. Further analysis show that the variation T-c is associated with Jahn-Teller energy and electronic band width, which also confirm the important role of the lattice polaron on the property of the manganite. These results not only provide a universal description of the dependence of the magnetism-resistivity correlation on T-c. but also demonstrate the importance of the accompanying occurrence of spin-lattice and charge-lattice couplings in the manganites.
- 出版日期2014-3
- 单位北京计算科学研究中心; 北京师范大学
