  Electrical generation of polarized spins in nonmagnetic materials is of great
interest for the underlying physics and device potential. One such mechanism 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. However, the microscopic mechanism and manifestation of CISS in
practical device structures remain controversial; in particular, the Onsager
relation is understood to preclude linear-response detection of CISS by a
ferromagnet. Here, we report direct evidence of CISS in two-terminal devices of
chiral molecules on the magnetic semiconductor (Ga,Mn)As: In vertical
heterojunctions of (Ga,Mn)As/AHPA-L molecules/Au, we observed characteristic
linear- and nonlinear-response magnetoconductance, which directly verifies spin
filtering by the AHPA-L molecules and spin detection by the (Ga,Mn)As. The
results constitute definitive signature of CISS-induced spin valve effect, a
core spintronic functionality, in apparent violation of the Onsager
reciprocity. The results present a promising route to semiconductor spintronics
free of any magnetic material.
