Linear and Nonlinear Two-Terminal Spin-Valve Effect from Chirality-Induced Spin Selectivity

Electrical generation of spin polarization in nonmagnetic materials is of broad interest for the underlying physics and device potential. One such scheme is chirality-induced spin selectivity (CISS), with which structural chirality leads to different electric conductivities for electrons of opposite spins. CISS has been reported for many chiral structures on different surfaces. However, the microscopic origin and transport mechanisms remain controversial. In particular, the fundamental Onsager relation was argued to preclude linear-response detection of CISS by a ferromagnet. Here, we report definitive observation of CISS-induced magnetoconductance in vertical heterojunctions of (Ga,Mn)As/AHPA-L molecules/Au, directly verifying spin filtering by the AHPA-L molecules via spin detection by the (Ga,Mn)As.¹ The pronounced and robust magnetoconductance signals enable a rigorous examination of its bias dependence, which shows both linear- and nonlinear-response components. The definitive identification of the linear-response CISS-induced two-terminal spin-valve effect places an important constraint for a viable theory of CISS and its device manifestations.

¹T. Liu, et al., ACS Nano, 2020 (doi: 10.1021/acsnano.0c07438)