Upper critical field, superconducting energy gaps, and Seebeck coefficient in La0.8Th0.2OFeAs

Prakash, J. ; Singh, S. J. ; Patnaik, S. ; Ganguli, A. K. (2009) Upper critical field, superconducting energy gaps, and Seebeck coefficient in La0.8Th0.2OFeAs Journal of Physics: Condensed Matter, 21 (17). No pp. given. ISSN 0953-8984

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Official URL: http://iopscience.iop.org/0953-8984/21/17/175705

Related URL: http://dx.doi.org/10.1088/0953-8984/21/17/175705

Abstract

We report the synthesis and characterization of a new electron-doped La-oxypnictide superconductor by partial substitution of lanthanum by thorium. The superconducting transition temperature at about 30.3 K was observed in La0.8Th0.2OFeAs which is the highest in La-based oxypnictide superconductors synthesized at ambient pressure. We find that the decrease in lattice parameters with Th doping in LaOFeAs is more drastic as compared to that obtained by high pressure (6 GPa) synthesis of oxygen deficient LaOFeAs. The resistivity and magnetic susceptibility measurements yield an upper critical field Hc2 (0) of 47 T. Partial substitution of Th in place of La induces electron doping as evidenced by negative Seebeck coefficient. The temperature dependent magnetic penetration depth data provides strong evidence for a nodeless low energy gap of 1.4 meV.

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
ID Code:91641
Deposited On:23 May 2012 14:25
Last Modified:19 May 2016 05:22

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