Giant Barrier of Atomic Diffusion Induced by Effectively Divergent Chemical Potential

Atomic diffusion in correlated materials plays a key role in controlling and optimizing the unique electronic properties, including superconductivity, metal-insulator transition, and complex magnetic behavior. Therefore, it’s essential to comprehend the interplay among electronic correlations, crystal structure, and atomic motion. In this study, we present a giant barrier of hydrogen diffusion in vanadium dioxide (VO₂), evidenced by an order-of-magnitude decrease of effective diffusivity. This unprecedented barrier is not solely attributed to the structural variance but is also linked to the decreased latent heat during the metal-insulator transition (MIT). Drawing a parallel to the MIT of VO₂ driven by compressive stress, where the reduced latent heat is associated with an intrinsic strain across the transition point, the diminished transition energy in the doping system results from the shifted effective chemical potential of the dopant in various phases. This introduces an added activation barrier for hydrogen diffusion from metallic to insulating VO₂. This generalized thermodynamic effect at the transition juncture may provide deeper insights into atomic diffusion in correlated materials and holds the potential to advance the design of diffusion-centric applications.