Detecting chirality in two-terminal electronic devices

The chirality-induced spin selectivity (CISS) effect concerns the interconversion of electronic charge and spin currents. In two-terminal (2T) devices containing a chiral (molecular) component and a ferromagnet, CISS has been detected as magnetoresistance (MR) signals, which, however, is forbidden by Onsager reciprocity in the linear response regime. Here, by unifying the description for coupled charge and spin transport in magnetic and chiral spin-charge converters, we uncover an elementary mechanism that breaks reciprocity and generates MR for nonlinear response. It requires (a) energy-dependent transport, and (b) energy relaxation in the device. The sign of the MR depends on the chirality, the charge carrier type, and the bias direction. Additionally, our formalism reveals how CISS can be detected in the linear response regime in magnet-free 2T devices, either by forming a chirality-based spin-valve using two or more chiral components, or by Hanle spin precession in devices with a single chiral component.