Chirality-induced spin selectivity and current-driven spin and orbital polarization in chiral crystals

Chirality is a fundamental property of great importance in physics, chemistry, and biology and has recently been found to generate unexpected spin polarization for electrons passing through organic molecules, known as chirality-induced spin selectivity (CISS). CISS shows promising application potential in spintronic devices, spin-controlled chemistry, and enantiomer separation. It focuses on organic molecules that exhibit poor electronic conductivity and inherent complexities, such as the debated role of spin-orbit coupling (SOC) at the molecule-metal interface. In this work, we go beyond organic molecules and study chiral solids with excellent electrical conductivity and intrinsic SOC. We demonstrate that electrons exhibit both spin and orbital polarization as they pass through chiral crystals. The spin polarization is proportional to SOC, while the orbital polarization is insensitive to SOC, indicating that the SOC converts the orbital polarization into spin polarization. The large spin polarization comes with strong electrical magnetochiral anisotropy in the magnetotransport of these chiral crystals (e.g., RhSi). Our work reveals the interplay of chirality, electron spin, and orbital in chiral crystals. These results will be helpful for further computational and experimental studies for the development of chiral solids for chirality-induced phenomena.