Applicability of the vortex-glass model for the single crystal Tl_0.4K_0.41Fe_1.71Se₂

We measure the current-voltage (I-V) characteristics for the single crystal of Tl_0.4K_0.41Fe_1.71Se₂ with the superconducting transition temperature (T_C) around 30.5 K, under a 10 T magnetic field applied perpendicular and parallel to the ab plane. We find that the shapes of the I-V isotherms are very different from the description by the vortex-glass (VG) model. Combining theoretical calculations and analysis of the ρ_H⊥ab-T and ρ_H||ab-T data, we give an explicit discussion over the suitability of the VG model for the A_0.8Fe₂Se₂ superconductors, and point out the possibility of the material acting as a convenient platform for re-examination and further study of the complex vortex behaviors in the layered superconductors.