Anisotropic flux pinning energy in FeSexTe1-x single crystals

• FeSexTe1 – x (x = 0.3, 0.4, 0.5, 0.6, 0.7) single crystals were prepared by the chemical reaction. The temperature dependence of the in-plane resistance R(T) of single crystals FeSexTe1 – x were measured.• Flux pinning energy was studied by Arrhenius relation and the modified thermally activated flux flow (TAFF) model. This result suggests that there is a crossover from single vortex pinning to collective creep pinning region with magnetic field increasing.• The anisotropy parameter of FeSe0.4Te0.6 was calculated by the means of using the ratio of Hc2 for the two major directions (H//c and H⊥c) and scaling by the equation Hc2GL(θ)=Hc2c/(cos2(θ)+γ−2sin2(θ)).

FeSexTe1 – x (x = 0.3, 0.4, 0.5, 0.6, 0.7) single crystals have been prepared by the chemical reaction of the elements. The field dependence of flux pinning energy shows a power law behavior, U∝H−α, where α displays a crossover at H ∼ 2 T from small value at low field to large value at high field for both magnetic fields perpendicular and parallel to c-axis. At same field, the flux pinning energy for H//ab-plane is higher than that for H//c-axis, showing an anisotropic behavior. The crossover maybe correspond to the flux pinning from single vortex pinning to collective pinning with magnetic field increasing. Based on the anisotropic G-L theory, the angular dependence of in-plane resistivity ρ   in different magnetic fields at fixed temperature can be scaled by the equation, Hc2GL(θ)=Hc2c/(cos2(θ)+γ−2sin2(θ)). The weak temperature dependence of anisotropic parameter γ near Tc was given for FeSe0.5Te0.5 and FeSe0.4Te0.6 crystals, respectively.