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

Haoyun Deng

Abstract:

Various mechanisms of electrical generation of spin
polarization in nonmagnetic materials have been a subject of broad
interest for their underlying physics and device potential in
spintronics. One such scheme is chirality-induced spin selectivity
(CISS), with which structural chirality leads to different electric
conductivities for electrons of opposite spins. The resulting effect of
spin filtering has been reported for a number of chiral molecules
assembled 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. The pronounced and robust magnetoconductance signals resulting from the use of a magnetic
semiconductor 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. The