2008/11/15 by P J Baker, P. J. Baker, S. R. Giblin +17
Materials Science · Physics and Astronomy · #Crystal (programming language) #Entropy (arrow of time) #Heat capacity #Heat transfer #Iron-based superconductors research #Lattice (music) #Physics of Superconductivity and Magnetism #Pnictogen #Specific heat #Superconductivity #Superconductivity in MgB2 and Alloys #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1088/1367-2630/11/2/025010
11 pages, 4 figures, submitted to New Journal of Physics focus issue on Iron-Based Superconductors
arxiv created 2008/11/15 · openalex publication_date 2009/02/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report heat capacity measurements of the pnictide materials SmFeAsO 1- x F x , NdFeAsO, LaFeAsO 1- x F x and LiFeAs. For SmFeAsO 1- x F x , with x close to 0.1, we use 3 He measurements to demonstrate a transfer of entropy from the peak at T N to a previously unidentified ∼2 K feature, which grows with increasing doping. Our results on the Sm samples are compared with a similarly doped La sample to elucidate the crystal field levels of the Sm 3+ ion at 0, 20 and 45 meV, which lead to a Schottky-like anomaly, and also show that there is a significant increase in the Sommerfeld coefficient γ when La is replaced by Sm or Nd. The lattice contribution to the heat capacity of the superconducting oxypnictides is found to vary negligibly with chemical substitution. We also present a heat capacity measurement of LiFeAs showing the feature at T c , which is significantly rounded and much smaller than the BCS value.