Upper critical field and fluctuation conductivity in the critical regime of doped SmFeAsO

I. Pallecchi, C. Fanciulli, M. Tropeano, A. Palenzona, M. Ferretti, A. Malagoli, A. Martinelli, I. Sheikin, M. Putti, and C. Ferdeghini
Phys. Rev. B 79, 104515 – Published 19 March 2009

Abstract

We measure magnetotransport of F-doped SmFeAsO samples up to 28 T and we extract the upper critical fields, using different criteria. In order to circumvent the problem of criterion-dependent Hc2 values, we suggest a thermodynamic estimation of the upper critical field slope dHc2/dT based on the analysis of conductivity fluctuations in the critical regime. A high field slope as large as 12T/K is thus extracted for the optimally doped sample. We find evidence of a two-dimensional lowest Landau level (LLL) scaling for applied fields larger than μ0HLLL8T. Finally, we estimate the coherence length values and we observe that they progressively increase with decreasing Tc. In all cases, the coherence length values along the c axis are smaller than the interplanar distance, confirming the two-dimensional nature of superconductivity in this compound.

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  • Received 30 January 2009

DOI:https://doi.org/10.1103/PhysRevB.79.104515

©2009 American Physical Society

Authors & Affiliations

I. Pallecchi1, C. Fanciulli1, M. Tropeano1, A. Palenzona2, M. Ferretti2, A. Malagoli1, A. Martinelli2, I. Sheikin3, M. Putti1,4, and C. Ferdeghini1

  • 1CNR-INFM-LAMIA, via Dodecaneso 33, 16146 Genova, Italy and Università di Genova, via Dodecaneso 33, 16146 Genova, Italy
  • 2DCCI, Università di Genova, via Dodecaneso 31, 16146 Genova, Italy and CNR-IMEM unità di Genova, via Dodecaneso 31, 16146 Genova, Italy
  • 3GHMFL, MPI-FKF/CNRS, 28 Avenue des Martyrs, BP 166, 38042 Grenoble, France
  • 4ASC, NHMFL, FSU, 2031 E. Paul Dirac Dr., Tallahassee, Florida 3231, USA

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Issue

Vol. 79, Iss. 10 — 1 March 2009

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