Hydrogen Chemisorption and Current-Induced Spin Polarization on NbP

Topological semimetals have been proposed as electrocatalytic platforms because their surface states may participate in adsorbate bonding and interfacial charge response. Here we examine this role for hydrogen chemisorption on NbP(001) by combining density functional theory, Wannier-based surface spectral functions, orbital projections, and projected crystal orbital Hamilton population analysis. An SOC on/off comparison allows us to examine two electronic regimes of the same surface: including nodal-line-derived surface states in the non-SOC limit and Weyl Fermi arcs in the SOC case. We find that SOC changes the hydrogen adsorption free energy only weakly, showing that the equilibrium adsorption descriptor is largely insensitive to the SOC-driven reorganization of the surface states. Momentum- and energy-resolved bonding analysis assigns the main H-surface stabilization to occupied local H-Nb hybridized states below the Fermi level. At $E_F$, the Fermi arcs provide the dominant hybridization channels that contribute to the state-resolved bonding pattern and transfer spin-textured character to the adsorbate, producing a finite H-projected current-induced spin polarization. Thus, NbP demonstrates that topological surface states can play a minor role in adsorption thermodynamics while governing Fermi-level hybridization and adsorbate-local current-induced spin polarization.

Source: arXiv:2606.16994v1 - http://arxiv.org/abs/2606.16994v1 PDF: https://arxiv.org/pdf/2606.16994v1 Original Link: http://arxiv.org/abs/2606.16994v1