Magnetic and magnetotransport studies of iron-chalcogenide superconductor Fe(Se0.4Te0.6)0.82: observation of thermally activated transport and flux jump

Abstract

The magnetic and magneto-transport behavior of the Fe-based superconductor of nominal composition Fe(Se0.4Te0.6)0.82 has been investigated. Different superconducting parameters such as critical fields, coherence length, penetration depth and the Ginzburg–Landau parameter (κ) have been estimated for the present compound. The large value of κ (∼253) is in line with the unconventional type-II nature of the studied superconductor. Thermally activated transport behavior in the presence of an external magnetic field across the superconducting transition region indicates a crossover from a single-vortex pinning regime to a collective flux creep regime at 50 kOe. The sample shows anomalous field dependence of flux flow resistance, which is presumably connected to the inherent superconducting state of the sample. The isothermal resistivity data as a function of external magnetic field show a signature of flux jump below the superconducting transition temperature (Tc). The effect of hydrostatic pressure on the superconducting properties of the compound has also been investigated and about 3 K shift in Tc has been observed with the application of 10 kbar of pressure.