In this talk, I will focus on my experimental studies in semiconductor and molecular spintronics. I will first briefly describe spin transport in a persistent photoconductor Si-doped Al0.3Ga0.7As, where we produced the first results of spin lifetimes at various carrier densities on one and the same device. I will then talk about molecular patterning and directed self-assembly of Au nanoparticles on GaAs .
Combining the expertise from these two projects, my main project is aimed at chirality-induced spin selectivity (CISS) in hybrid semiconductor/molecular devices . We obtained definitive evidence of spin-selective electron transport in two-terminal vertical junctions of (Ga,Mn)As/AHPA-L molecules/Au. The use of the ferromagnetic semiconductor (Ga,Mn)As resulted in the realization of a pronounced and stable CISS-induced spin-valve effect, which facilitated, for the first time, a comprehensive and rigorous study of its bias dependences. The results are in apparent violation of the fundamental Onsager reciprocity, and constitutes a significant constraint on any viable theory of the CISS and its device manifestations. Finally, I will present probable observation of the Hanle effect and dynamic nuclear polarization in the junctions of n-GaAs/AHPA-L molecules/Au, which are free of any magnetic material. Our results have practical implication in electrically creating and possibly detecting spin polarized current in semiconductors without using any magnetic material.
 T. Liu, et al., ACS Appl. Mater. Interfaces 9, 43363 (2017).
 T. Liu, et al., ACS Nano 14, 15983 (2020).