Unconventional resistive transitions in the extreme type-II superconductor Tl2Mo6Se6

Abstract

A study of the resistive transition into the superconducting state of the quasi-1D superconductor Tl2Mo6Se6 (Tc=5K) has revealed a broadening effect under applied magnetic field similar to that seen in the high-Tc cuprates. Using anisotropic Ginzburg–Landau theory we calculate a Ginzburg number Gi≈1.8×10−5, corresponding to a critical region of width ∼0.09mK, which is ∼18000 times smaller than the measured ΔTc2. This proves that fluctuations of the order parameter are not the predominant factor responsible for the broadening of the transition and suggests the possible absence of a macroscopic phase coherence over a wide region of the vortex phase diagram.