Panwar, N. and Pandya, D. K. and Rao, A. and Wu, K. K. and Kaurav, N. and Kuo, Y. -K. and Agarwal , S. K. (2008) Electrical and thermal properties of Pr2/3(Ba1−xCsx)1/3MnO3 manganites. European Physical Journal B: Condensed Matter and Complex Systems , 65 (2). pp. 179-186. ISSN 1434-6036

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Abstract

Electrical and thermal properties of Pr2/3(Ba1−x Cs x )1/3MnO3 (0 ≤ x ≤ 0.25) manganite perovskites are reported here. Two insulator-metal (I-M) transitions (T P1 &T P2) are observed in the electrical resistivity (ρ) of the pristine Pr2/3Ba1/3MnO3 (PBMO) sample, and they are systematically shifted to lower temperatures with increasing Cs substitution. An upturn in ρ is noticed below 50 K in these perovskites, presumably due to the combined effect of weak localization, electron-electron and electron-phonon scattering. It is found that the absolute value of room-temperature thermoelectric power (TEP) gradually decreases with increasing Cs content, implying the annihilation of the charge carriers with doping. An analysis of the electrical resistivity and thermoelectric power data indicates that the paramagnetic insulating state above T P1 is governed by the small polaron hopping due to a non-adiabatic process. It is argued that the electron-magnon scattering processes are responsible for low temperature metallic behavior of TEP. A distinct specific heat peak below T P1 is observed, attributed to the magnetic ordering, and its broadening with Cs-doping corresponds to the increase of magnetic inhomogeneity. Further, the temperature variation of thermal conductivity and the low temperature plateau in κ has been associated with the delocalization of Jahn-Teller polarons and transition from Umklapp scattering to a defect-limited scattering, respectively.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/S Springer Verlag.
Subjects:	Physics
Divisions:	UNSPECIFIED
Depositing User:	Ms Neetu Chandra
Date Deposited:	06 Jan 2014 13:33
Last Modified:	06 Jan 2014 13:33
URI:	http://npl.csircentral.net/id/eprint/1004

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