Ultrafast Inverse Chiral Induced Spin Selectivity in Chiral Perovskite and CISS symmetry

Chirality-induced spin selectivity (CISS) enables room-temperature control over spin, charge, and light in chiral semiconductors, yet the dynamic mechanisms governing spin-charge interconversion remain poorly understood. Here, we discuss terahertz emission spectroscopy (TES) as a non-contact, time-resolved probe to map spin-to-charge conversion in ferromagnet/chiral perovskite heterostructures. TES reveals that ICISS exhibits symmetry behavior analogous to CISS: the direction of the induced charge current reverses upon switching either the chirality or magnetization. These findings directly demonstrate the intrinsic coupling between spin and charge currents in chiral systems and impose constraints on the CISS mechanism. We discuss the symmetry of both CISS and ICISS measurements and argue that they obey a form of PT symmetry. The implications for the CISS mechanism will be discussed. We propose that spin/charge accumulation at a chiral/ferromagnet interface drives this interconversion, where injection of either spin (ICISS) or charge (CISS) perturbs the equilibrium spin configuration, necessitating compensatory transport. Our results establish TES as a powerful tool for probing ultrafast spin dynamics and highlight the potential of chiral heterostructures for spintronic applications.