Calorimetric Study on the Superconducting Order Parameter of the Pnictides Superconductors Tuson Park (Sungkyunkwan University) Since the discovery of the Fe-based pnictides, significant amount of work has been expended to determine the superconducting order parameter because it is closely tied to the superconducting (SC) mechanism. However, the nature of the SC order is far from consensus partly due to strong doping dependence of SC properties and/or specific features of the measurement techniques that probe preferentially a fraction of the total Fermi surface. Low-temperature specific heat, which is

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Nov 15, 2013 (3 years and 7 months ago)

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Calorimetric Study on the Superconducting Order Parameter of the Pnictides Superconductors

Tuson Park (Sungkyunkwan University)


Since the discovery of the Fe
-
based pnictides, significant amount of work has been expended to
determine the superconducting
order parameter because it is closely tied to the superconducting
(SC) mechanism. However, the nature of the SC order is far from consensus partly due to strong
doping dependence of SC properties and/or specific features of the measurement techniques that
probe preferentially a fraction of the total Fermi surface. Low
-
temperature specific heat, which is
proportional to the electronic density of states, has provided critical information on determining
the SC order parameter of various classes of superconduct
ors, including the high
-
Tc cuprates. In
Fe
-
based pnictides superconductors, however, interpretation of the specific heat at low
temperatures has been difficult because of a Schottky
-
like upturn at the lowest temperatures. In
this talk, we present low
-
tempe
rature specific heat measurements of the slightly overdoped
Ba(Fe,Co)2As2, where there is not any visible upturn down to the lowest measured temperature
400 mK and up to the highest measured magnetic field of 9 Tesla. The temperature dependence
as well as
the magnetic field dependence of the specific heat is consistent with the presence of
nodes on parts of the Fermi surface. Preliminary results of the field
-
rotational specific heat, which
could determine the precise position of the nodal points, will be di
scussed, too.


This work has been done in collaboration with D.
-
J. Jang, S. Ju, J. B. Hong, Z. Yang, J. H. Han, Y. S.
Kwon (SKKU), A. B. Vorontsov (MSU), I. Vekhter (LSU), K. Gofryk, F. Ronning, and J. D. Thompson
(LANL).