2008/06/26 by Y. Kohama, Yoshimitsu Kohama, Yoichi Kamihara +12
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Physics of Superconductivity and Magnetism #Rare-earth and actinide compounds #cond-mat.supr-con
paper · pdf · doi:10.1209/0295-5075/84/37005
published as Europhys Letters, 84 (2008) 37005 · 12 pages and 4 figures
arxiv created 2008/06/26 · openalex publication_date 2008/10/24 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
The electrical resistivity and Hall coefficient of LaFeAsO 0.95 F 0.05 polycrystalline samples were measured in pulsed magnetic fields up to μ 0 H =60 T from room temperature to 1.5 K. The resistance of the normal state shows a negative temperature coefficient (dρ/ d T <0) below 70 K for this composition, indicating insulating ground state in underdoped LaFeAsO system in contrast to heavily doped compound. The charge carrier density obtained from Hall effect can be described as constant plus a thermally activated term with an energy gap Δ E =630 K. The upper critical field, H c2 , estimated from resistivity measurements, exceeds 75 T with zero-field T c =26.3 K, suggesting an unconventional nature for superconductivity.