Chirality induced spin selectivity in chiral crystals

Qun Yang, Yongkang Li, Claudia Felser, Binghai Yan

Published 2023-12-07Version 1

Chirality is a fundamental property of great importance in physics, chemistry, and biology. Recently, an exotic phenomenon known as chirality-induced spin selectivity (CISS), in which electrons with a particular spin can pass through chiral molecules, has shown promising application potential in spintronic devices, spin control chemistry, and enantiomer separation, among others. However, current CISS studies focus mainly on chiral organic molecules with poor electronic conductivity and inherent complexities, such as the controversial role of SOC at the molecule-metal interface. In contrast, chiral inorganic materials with excellent electrical conductivity, intrinsic SOC, homochiral crystal structure, and rich electronic properties open up new possibilities for advancing CISS studies. In this work, we demonstrate that electrons exhibit both spin and orbital polarization as they pass through chiral crystals. Both polarizations increase with material thickness until approach bulk properties. The spin polarization correlates with the SOC strength, while the orbital polarization is SOC insensitive. Furthermore, our results reveal a substantial spin polarization ratio in Te and significant electrical magneto-chiral anisotropy in RhSi. Though the latter is usually employed to probe the former, the results show a clear difference between these two quantities. Our work reveals the interplay of chirality, electron spin, and orbital in chiral crystals, paving the way for the development of chiral inorganic materials for CISS applications.