Bhattacharya, Dipten and Chakraborty, Amitava and Maiti, Himadri Sekhar (1999) Evidence of relaxation of Jahn-Teller polarons above T-C in La1-xSrxMnO3 (0.1 < x <= 0.5). Journal of Physics-Condensed Matter, 11 (30). pp. 5845-5853. ISSN 0953-8984

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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.

Item Type: Article
Subjects: Electronics
Depositing User: Bidhan Chaudhuri
Date Deposited: 19 Jun 2012 06:46
Last Modified: 19 Jun 2012 06:46

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