Chiral electrons and spin selectivity at chiral-achiral interfaces

Abstract: Chiral molecules can selectively transport electrons of a particular spin orientation, yet the underlying mechanism remain poorly understood. Here, we present theoretical evidence that electrons propagating through chiral materials with screw symmetry exhibit chirality themselves and carry symmetry-induced pseudo-angular momentum (PAM) which must be characterized by both spin and orbital components. The chiral electron transport is PAM polarized, with counterpropagating states exhibiting opposite PAM. At chiral-achiral interfaces, the PAM polarization is converted to spin polarization due to wave function matching, thereby establishing a novel principle for the chiral-induced spin selectivity.