Thermally activated flux flow in Fe1.06Te0.6Se0.4 single crystal

• Resistivity of Fe1.06Te0.6Se0.4 is investigated around superconducting transition region in different magnetic fields.
• Based on a theoretical prediction of the resistivity and experimental data, thermally activated energy is studied.
• The study shows that Arrhenius curve slopes are directly related to but not equal to thermally activated energy.
• Modified thermally activated flux flow model is suggested to use, where the temperature dependence of 2ρcU/T is considered.
• Modified TAFF method results are in good agreement with very high critical current density values from experimental data.

Resistivity of Fe1.06Te0.6Se0.4 single crystal is investigated around superconducting transition region in different magnetic fields. The thermally activated energy (TAE) is analysed using the Arrhenius relation and modified thermally activated flux flow (TAFF) model. The results indicate that the Arrhenius curve slopes are directly related to but not equal to TAE. Therefore, use of the modified TAFF model is suggested, ρ(T,B) = ρ0f exp(−U/T), where the temperature dependence of the pre-factor ρ0f = 2ρcU/T and the nonlinear relation of the TAE should be considered. The modified TAFF method results are in good agreement with the very high critical current density values from the experimental data. It was found that the vortex glass has a narrow region, and it depends weakly on magnetic field. The vortex phase diagram was determined based on the evolution of the vortex-glass transition temperature with magnetic field and the upper critical field.