Quasi-two-dimensional vortex matter in the ThH 10 superhydride

A comprehensive study of the vortex phases and vortex dynamics is presented for a recently discovered high-temperature superconductor ${\mathrm{ThH}}₁₀$ with ${T}_{\mathrm{C}}=153\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ at 170 GPa. The obtained results strongly suggest a quasi-two-dimensional (2D) character of the vortex-glass phase transition in ${\mathrm{ThH}}₁₀$. The activation energy yields a logarithmic dependence ${U}₀\ensuremath{\propto}ln(H)$ on magnetic field in a low-field region and a power-law dependence ${U}₀\ensuremath{\sim}{H}^{\ensuremath{-}1}$ in a high-field region, signaling a crossover from 2D regime to three-dimensional collective pinning regime, respectively. Additionally, a pinning force-field dependence showcases dominance of surface-type pinning in the vicinity of ${T}_{\mathrm{C}}$. Thermal activation energy $({U}₀)$, derived within thermally activated flux-flow theory, takes very high values above $2\ifmmode\times\else\texttimes\fi{}{10}⁵\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ together with the Ginzburg number $Gi=0.039--0.085$, which is lower only than those of BiSrCaCuO cuprates and 10--3--8 family of iron-based superconductor. This indicates the enormous role of thermal fluctuations in the dynamics of the vortex lattice of superhydrides, the physics of which is similar to the physics of iron-based and copper-based high-temperature superconductors.