Low-temperature specific heat (SH) is measured on Ba(Fe 1-xCox)2As2 single crystals in a wide doping region under different magnetic fields. For the overdoped sample, we find the clear evidence for the presence of the T2 term in the SH data, which is absent both for the underdoped and optimal doped samples, suggesting the presence of line nodes in the energy gap of the overdoped samples. Moreover, the field-induced electronic specific heat coefficient Δγ(H) increases more quickly with the field for the overdoped sample than the underdoped and optimal doped ones, giving more support to our arguments. Our results suggest that the superconducting gap(s) in the present system may have different structures strongly depending on the doping regions.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Aug 5|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics