Effect of thermal fluctuations on the flux motion and vortex dynamic in (Li0.8Fe0.2)OHFeSe single crystals

Abstract

We present a qualitatively investigation on the influence of thermal fluctuation on flux motion and vortex dynamic of (Li0.8Fe0.2)OHFeSe single crystals. The importance of thermal fluctuations has been assessed through the Ginzburg number Gi. The resistivity in the mixed state for (Li0.8Fe0.2)OHFeSe exhibits a thermally activated behavior investigated by TAFF theory. The field-dependent activation energy follows the relation U0 (H) ∼ H-α. The appearance of crossover at 2 T is related to the different pinning mechanisms. Single-vortex pinning occurs in the low fields range at H < 2 T, and collective pinning dominates in the region of field higher than 2 T. The vortex phase diagram from glass state to liquid state has been discussed based on the vortex-glass theory. Due to the influence of thermal fluctuations, there is a broad vortex liquid regime in the vortex phase diagram.

Keywords

• Thermal fluctuations
• Flux flow
• Vortex dynamic
• Pinning mechanisms