The energy gap of the compound FeSe0.5Te0.5 determined by specific heat and point contact spectroscopy

Abstract

The superconductor $FeSe_{0.5}Te_{0.5}$ was studied with Point Contact spectroscopy and specific heat in polycrystalline samples. The transition temperature determined by magnetic measurement was $T_C =14.5$ K. The size of the energy gap measured by junctions is $\Delta = 1.9$ meV, whereas the gap determined by the specific heat measurements was $\Delta = 2.3 $ meV. The gap evolution with temperature follows BCS, the ratio 2$\Delta$/$K_BT_C$ has values between 2.88 $\leq 2\Delta/K_BT_C \leq 3.04$. The compound was grown by solid state synthesis in quartz ampoules under vacuum at 950 C. Crystal structure was characterized by X-ray diffraction. The superconducting properties were characterized by magnetization, resistivity and specific heat. This superconductor shows an isotropic energy gap as observed with the fitting of the specific heat at low temperature.