In order to investigate details of the superconducting (SC) gap in the iron-chalcogenide superconductors, the specific heat, C , of FeSe1-x Tex with x = 0.6 -1 has been measured in magnetic fields. Using the two-gap model, it has been found that the smaller SC gap is significantly depressed by the application of magnetic field, resulting in the increase of the slope of the C/T vs T 2 plot at low temperatures. From the specific-heat measurements at very low temperatures down to 0.4 K, it has been found that the enhancement of the residual electronic-specific-heat-coefficient in the ground state, £0, by the application of magnetic field is much smaller than that expected for superconductors with the typical s- or d-wave SC paring symmetry, which is in sharp contrast to the significant enhancement of £0 observed in the iron-pnictide superconductors. These results are discussed in relation to the multi-band effect in the iron-based superconductors.
ASJC Scopus subject areas
- Physics and Astronomy(all)