No abstract

Given the challenges in experimental studies of uranium, the heaviest naturally occurring metal, we present first-principles calculation for the spin-dependent transport. Showing the largest atomic spin-orbit coupling we explore the ability of various crystal phases to maximise the charge to spin conversion using a full relativistic Korringa-Kohn-Rostoker Greens function method. The transport theory is based on a semi classical description where intrinsic and extrinsic, skew scattering, contributions can be separated easily. In addition to the various crystal phases we analyse the effect of substitutional impurities for γ, hcp, as well as the α-phase. We predict a very high, 10 4 (Ωcm) −1 , spin Hall conductivity for the meta-stable hcp-U phase, a giant value 5 times larger than for the conventional spin Hall material Pt. We estimated an efficiency of charge-to-spin current conversion of up to 30%. The spin diffusion length, a crucial parameter in any application, is predicted to be in the range from 3 − 6.5nm, compatible with other charge-to-spin conversion materials. Relating our work to the sparse experimental results, our calculations suggest a γ phase in the thin film rather than the experimentally expected α phase.

Superionic conductors have great potential as solid-state electrolytes, but the physics of type-II superionic transitions remains elusive. In this study, we employed molecular dynamics simulations, using machine learning force fields, to investigate the type-II superionic phase transition in α-Li 3 N. We characterized Li 3 N above and below the superionic phase transition by calculating the heat capacity, Li + ion self-diffusion coefficient, and Li defect concentrations as functions of temperature. Our findings indicate that both the Li + self-diffusion coefficient and Li vacancy concentration follow distinct Arrhenius relationships in the normal and superionic regimes. The activation energies for self-diffusion and Li vacancy formation decrease by a similar proportion across the superionic phase transition. This result suggests that the superionic transition may be driven by a decrease in defect formation energetics rather than changes in Li transport mechanism. This insight may have implications for other type-II superionic materials.

Superionic conductors have great potential as solid-state electrolytes, but the physics of type-II superionic transitions remains elusive. In this study, we employed molecular dynamics simulations, using machine learning force fields, to investigate the type-II superionic phase transition in α-Li3N. We characterised Li3N above and below the superionic phase transition by calculating the heat capacity, Li+ ion self-diffusion coefficient, and Li defect concentrations as functions of temperature. Our findings indicate that both the Li+ self-diffusion coefficient and Li vacancy concentration follow distinct Arrhenius relationships in the normal and superionic regimes. The activation energies for self-diffusion and Li vacancy formation decrease by a similar proportion across the superionic phase transition. This result suggests that the superionic transition may be driven by a change in defect formation behaviour, rather than changes in Li transport mechanism. This insight may hold implications for other type-II superionic materials.