Spontaneous spin selectivity and linear magnetoelectric effect in chiral molecules

Chirality-induced spin selectivity (CISS) has been extensively studied over the past two decades. While current-induced spin polarization in chiral molecules is widely recognized as the fundamental principle of the CISS, only a few studies have been reported on bias-current-free CISS, where there is no bias electric current in chiral molecules. In this paper, we discuss the microscopic origin of bias-free CISS using chiral molecule/ferromagnet bilayer systems. Recent studies on the chirality-induced exchange bias and current-in-plane magnetoresistance (CIP-MR) effects indicate that chiral molecules possess thermally driven broken-time-reversal symmetry at the interface, which induces bias-current-free CISS, i.e. a spontaneous effective magnetic field in the system. We also discuss the possibility of the linear magnetoelectric effect of chiral molecules at the interface and its potential impact on the observed CISS phenomena.