Enhanced vortex pinning with possible antiferromagnetic order in FeSe under pressure

초록

The strong coupling between magnetic, structural, and electronic degrees of freedom is a prominent feature of Fe-based superconductors. However, the relationship between the degrees of freedom and vortex dynamics remains unclear. In this paper, we measure the vortex pinning energy U-0/k(B) within the thermally activated flux flow regime with respect to the pressure-induced phases in a FeSe single crystal. We show that the dependence of U-0/k(B) on pressure, measured at a magnetic field higher than the crossover field Hcr, follows a trend like those of critical temperature T-c(p) and the average Fermi velocity v over line (upsilon) over bar (F)(p). On the other hand, at magnetic fields lower than H-cr, U-0/k(B) increases remarkably before reaching the pressure at which antiferromagnetic (AFM) long-range order occurs. Our results suggest the presence of additional pinning sites, possibly AFM domain boundaries, correlated with the enhanced U-0/k(B). In addition, in this paper, we provide a universal description of the vortex dynamics in FeSe.

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