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Thermal transport in (Y, Gd)Ba2(Cu1−xMnx)3O7−δ for x � 0.02

Gahtori, Bhaskar and Lal, Ratan and Agarwal, S K and Ahsan, M A H and Rao, Ashok and Lin, Y F and Sivakumar, K M and Kuo, Y K (2007) Thermal transport in (Y, Gd)Ba2(Cu1−xMnx)3O7−δ for x � 0.02. Journal of Physics:Condensed Matter, 19.

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Abstract

Thermal conductivity κ(T ) and thermoelectric power S(T ) studies on (Y, Gd)Ba2(Cu1−xMnx )3O7−δ (x � 0.02) superconductors are presented here. Thermal conductivity for all the samples exhibits a hump below the super conducting transition temperature Tc. The peak height of the hump decreases with the Mn content in both the Y- and Gd-based systems, barring GdBa2(Cu0.99Mn0.01)3O7−δ. The peak height reduction in the Gd-based cuprates is much faster (∼one fourth) compared to the Y-based samples. The thermoelectric power (TEP) of the Y-based samples for x � 0.0075 is electron like (up to ∼140 K) whereas it turns to hole-like even at x = 0.005 for the Gd-based system. On the basis of the structure of the thermal conductivity hump, and of the electron- or hole-like nature of the thermopower, it has been argued that, in the Y-based system up to x = 0.0075, Mn produces qualitatively the same effect as Gd in the Gd-based system. An analysis of the thermal conductivity data in terms of lattice theory, and the TEP data in terms of a narrow-band picture, has been made to invoke the role of Mn in these systems. Boundary scattering, point defects and sheet-like faults (from κ(T ) data analysis) and chemical potential (from S(T ) data analysis) support different roles of Mn for x � 0.0075 and x > 0.0075.

Item Type: Article
Subjects: Engineering > MIT Manipal > Physics
Depositing User: MIT Library
Date Deposited: 07 Mar 2014 11:03
Last Modified: 07 Mar 2014 11:03
URI: http://eprints.manipal.edu/id/eprint/139037

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