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Two-gap and paramagnetic pair-breaking effects on upper critical field of SmFeAsO$_{0.85}$ and SmFeAsO$_{0.8}$F$_{0.2}$ single crystals

Authors :
Lee, Hyun-Sook
Bartkowiak, Marek
Park, Jae-Hyun
Lee, Jae-Yeap
Kim, Ju-Young
Sung, Nak-Heon
Cho, B. K.
Jung, Chang-Uk
Kim, Jun Sung
Lee, Hu-Jong
Publication Year :
2009

Abstract

We investigated the temperature dependence of the upper critical field [$H_{c2}(T)$] of fluorine-free SmFeAsO$_{0.85}$ and fluorine-doped SmFeAsO$_{0.8}$F$_{0.2}$ single crystals by measuring the resistive transition in low static magnetic fields and in pulsed fields up to 60 T. Both crystals show that $H_{c2}(T)$'s along the c axis [$H_{c2}^c(T)$] and in an $ab$-planar direction [$H_{c2}^{ab}(T)$] exhibit a linear and a sublinear increase, respectively, with decreasing temperature below the superconducting transition. $H_{c2}(T)$'s in both directions deviate from the conventional one-gap Werthamer-Helfand-Hohenberg theoretical prediction at low temperatures. A two-gap nature and the paramagnetic pair-breaking effect are shown to be responsible for the temperature-dependent behavior of $H_{c2}^c$ and $H_{c2}^{ab}$, respectively.<br />Comment: 21 pages, 8 figures

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.0908.1267
Document Type :
Working Paper
Full Text :
https://doi.org/10.1103/PhysRevB.80.144512