APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011;
Dallas, Texas
Abstract: D26.00007 : Electronic specific heat of the iron chalcogenide superconductor Fe(Te$_{0.55}$Se$_{0.45})$
4:06 PM–4:18 PM
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Author:
We report specific heat studies of superconducting
Fe(Te$_{0.55}$Se$_{0.45})$[1]. We have obtained the electronic
specific heat
by subtracting the phonon contribution evaluated from the
normalization of
the phonon specific heat of a non-superconducting reference sample
(Fe$_{0.9}$Cu$_{0.1})$(Te$_{0.55}$Se$_{0.45})$. Our results show
that the
superconducting ground state is accompanied by unpaired
quasiparticles, as
in FeAs superconductors, with \textit{$\gamma $}$_{0
}$\textit{$\sim $}2.3 mJ/mol K$^{2}$. The temperature
dependence of the electronic specific heat $C_{es}(T)$/$T$ can be
well fitted
using either a single s-wave gap model with 2\textit{$\Delta $}=
5.2 k$_{B}T_{c}$ or a
two-gap model with 2\textit{$\Delta $}$_{1}$/k$_{B}T_{c }$= 5.8
and 2\textit{$\Delta $}$_{2}$/k$_{B}T_{c}$ =
4.0; the two-gap model fitting is slightly better than the single
gap
fitting. Such large gaps, together with a large specific heat
jump $\Delta
C(T_{c})$/$T_{c}\sim $57.3 mJ/mol K$^{2}$, suggest a strong-coupling
superconducting state. While $C_{es}(T)$/$T$ exhibits isotropic
s-wave gap
behavior, the magnetic field-induced change in the electronic
specific heat
$\Delta $\textit{$\gamma $}($H)$ exhibits sublinear field
dependence, implying the
superconducting pairing in iron chalcogenide superconductors also
involves a
multiple band effect, as seen in pnictide superconductors.
[1] M. H. Fang, H. M. Pham, B. Qian, T. J. Liu, E. K. Vehstedt,
Y. Liu, L.
Spinu, and Z. Q. Mao, Superconductivity close to magnetic
instability in
Fe(Se$_{1-x}$Te$_{x})_{0.82}$, Phys. Rev. B 78, 224503 (2008).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.D26.7