Chirality induced spin selectivity: a minimal model

Chirality-induced spin selectivity (CISS) indicates a wide variety of phenomena occurring in chiral media, where the spin orientation of an electron affects its behavior. Various experiments have demonstrated remarkable efficiency in spin filtration, even at the single molecule level.. Driven by the potential for applications, tremendous efforts have been devoted to elucidate the mechanism behind CISS, without reaching a quantitative agreement with experiments. In this work, we investigate CISS in electron transport, relying on a modified Hubbard model to include spin-orbit coupling (SOC). Specifically, current is driven through the system via the current-constrained approach to achieve a steady-state condition where spin current and spin polarization can be directly observed. We analyze the role of the connectivity among the sites, and of vibrational degrees of freedom beyond the standard mean-field approximation, critically asssessing the minimal ingradients a model must have to observe spin polarization.