Chirality-induced magnet-free spin generation in a semiconductor*

Efficient interconversion of electronic charge and spin is central to the fundamental research and device applications in spintronics and quantum information. While spin generation in semiconductors is often realized through electrical injection from a ferromagnet, there are notable advantages to exploring nonmagnetic approaches for creating spin polarization. One such approach is via chirality-induced spin selectivity (CISS), where structural chirality induces spin polarization in the direction of the electrical current. In this study, we employ CISS to efficiently generate spin accumulation in n-doped GaAs by electric current injection from a normal metal (Au) electrode through a self-assembled monolayer of chiral molecules (alpha-helix L-polyalanine, AHPA-L). Our previous work has already demonstrated that CISS can yield significant spin valve signals in similar devices with (Ga, Mn)As acting as the spin analyzer^1,2. The resulting spin polarization is detected as a Hanle effect in the n-GaAs, which follows a distinct universal scaling with temperature and bias current. The experiment represents a definitive observation of CISS in a fully nonmagnetic device structure, demonstrating its capacity to generate spin accumulation in a conventional semiconductor. The results provide valuable insights into the physical mechanism of CISS and introduce a novel pathway to magnet-free semiconductor spintronics.