Electronic and Spin States at Edges of Finite $p$-orbital Helical Atomic Chain

Abstract: In connection to the chiral-induced spin-selectivity (CISS) effect, we theoretically analyze the electronic and spin states of edges of a finite $p$-orbital helical atomic chain with the intra-atomic spin-orbit interaction (SOI). This model can host the spin-filtering state in which two up spins propagate in one direction and two down spins propagate in the opposite direction without breaking the time-reversal symmetry. The enhancement of charge modulations concentrated at the edges due to the evanescent states is induced, although the spin density is absent because of the time-reversal symmetry (TRS). A Zeeman field at an edge of the atomic chain, which breaks the TRS, yields a finite spin polarization, whose direction depends on the chirality of the molecule. The chirality change induces a reasonable amount of the energy difference, which may provide an insight into the enantioselective adsorption of chiral molecules on the ferromagnetic surface.