Quasi Two-dimensional Vortex Matter in ThH$_{10}$ Superhydride

TL;DR

This study investigates the vortex phases and dynamics in ThH$_{10}$ superhydride, revealing a quasi-2D vortex glass transition, crossover behaviors, and significant thermal fluctuation effects akin to high-temperature superconductors.

Contribution

It provides the first detailed analysis of vortex matter in ThH$_{10}$, highlighting its quasi-2D nature and complex pinning and fluctuation phenomena at high pressures.

Findings

Vortex glass transition exhibits quasi-2D character.

Crossover from 2D to 3D vortex pinning regimes observed.

High thermal activation energies indicate strong thermal fluctuations.

Abstract

A comprehensive study of the vortex phases and vortex dynamics is presented for a recently discovered high-temperature superconductor ThH$_{10}$ with $\textit{T}$$_C$ = 153 K at 170 GPa. The obtained results strongly suggest a quasi two-dimensional (2D) character of the vortex glass phase transition in ThH$_{10}$. The activation energy yields a logarithmic dependence $\textit{U}$$_0$ $\propto$ ln($\textit{H}$) on magnetic field in a low field region and a power law dependence $\textit{U}$$_0$ ~ $\textit{H}$$^{-1}$ in a high field region, signaling a crossover from 2D regime to 3D collective pinning regime, respectively. Additionally, a pinning force field dependence showcases dominance of surface-type pinning in the vicinity of $\textit{T}$$_C$. Thermal activation energy ($\textit{U}$$_0$), derived within thermally activated flux flow (TAFF) theory, takes very high values above 2$\times$10$^5$ K together with the Ginzburg number $\textit{Gi}$ = 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 unconventional high-temperature superconductors.