Evidence of relaxation of Jahn-Teller polarons above TC in La1-xSrxMnO3 (0.1 < x ≤ 0.5)

被引:6
作者
Bhattacharya, D
Chakraborty, A
Maiti, HS
机构
[1] Natl Phys Lab, Cryogen Div, New Delhi 110012, India
[2] Cent Glass & Ceram Res Inst, Electroceram Lab, Kolkata 700032, W Bengal, India
关键词
D O I
10.1088/0953-8984/11/30/313
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
We report the resistivity (rho)-temperature (T) patterns in La1-xSrxMnO3 (0.1 < x less than or equal to 0.5) systems over a temperature regime of 20-1273 K. Apart from a general trend of metallic rho-T pattern below Te (Curie point) and insulating above it, are have observed a re-entrant metallic rho-T pattern beyond a characteristic temperature T* above T-C for the compositions 0.25 less than or equal to x less than or equal to 0.50. Such behaviour possibly reflects the relaxation of Jahn-Teller (JT) polarons (which form as a result of splitting of Mn3+ outer levels and associated distortion in MnO6 octahedra) at a higher temperature. The polaron formation energy E-JT has been calculated from fitting a simple two-channel conduction model with the resistivity data. It appears to vary significantly with the Sr2+ ion concentration (x) or the concentration of JT-active Mn3+ ions which reflects the variation of the extent of Jahn-Teller coupling. The relaxation of polarons and the change in the behaviour of rho-T pattern above T* are not associated with any commensurate magnetic transition which seems to be supporting the notion that Jahn-Teller polarons influence the properties like T-C, conductivity, magnetoresistivity etc significantly.
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页码:5845 / 5853
页数:9
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