# The Isotope Effect and Critical Magnetic Fields of Superconducting YH$_{6}$: A Migdal-Eliashberg Theory Approach

## TL;DR

This study uses Migdal-Eliashberg theory and density functional calculations to show that YH$_6$ exhibits strong-coupling conventional superconductivity with high critical fields and isotope effects, challenging its perceived anomalous behavior.

## Contribution

The paper demonstrates that YH$_6$'s superconducting properties are consistent with strong-coupling conventional theory, extending understanding to related metal hydrides.

## Key findings

- YH$_6$ shows high critical magnetic fields.
- Isotope effect aligns with strong-coupling superconductivity.
- Strong-coupling corrections modify BCS values for key parameters.

## Abstract

The emergence of near-ambient temperature superconductivity under pressure in the metal hydride systems has motivated a desire to further understand such remarkable properties, specifically critical magnetic fields. YH$_6$ is suggested to be a departure from conventional superconductivity, due to apparent anomalous behavior. Using density functional calculations in conjunction with Migdal-Eliashberg theory we show that in YH$_6$ the critical temperature and the isotope effect under pressure, as well as the high critical fields, are consistent with strong-coupling conventional superconductivity; a property anticipated to extend to other related systems. Furthermore, the strong-coupling corrections occur to the expected BCS values for the Ginzburg-Landau parameter ($\kappa_{1}(T)$), London penetration depth ($\lambda_{L}(T)$), electromagnetic coherence length ($\xi(T)$), and the energy gap ($\Delta_{0}$).