Chirality-induced Spin Selectivity in a Two-terminal Semiconductor Device

Electrical generation of spin polarization in semiconductors is of great interest for the device potential in spintronics. One such mechanism is chirality-induced spin selectivity (CISS), with which structural chirality leads to different electric conductivities for electrons of opposite spins. CISS has been widely reported for chiral molecule assemblies on metal surfaces. However, theoretical understanding of the microscopic mechanism and manifestation of CISS in specific device structures remain controversial.^1,2 Here, we report direct evidence of CISS in two-terminal devices of heterojunctions of (Ga,Mn)As/AHPA-L molecules/Au. The (Ga,Mn)As layer acts as a spin analyzer for electrons injected from the Au electrode through the AHPA-L monolayer. The CISS of AHPA-L and spin injection into the (Ga,Mn)As are manifested as sharp changes in the junction conductance at the coercive fields of the (Ga,Mn)As. The observations provide a definitive signature of CISS-induced spin valve effect in a two-terminal device. Theoretical implications of the effect and its bias dependence will be discussed.
¹X. Yang, et al., Phys. Rev. B 99, 24418 (2019).
²S. Dalum and P. Hedegård, Nano Lett. 19, 5253 (2019).