Spin–Chiral Lattice–Photon Coupling in Organic Chiral Cocrystals with Temperature-Induced Chirality Inversion

Chirality plays an essential role in emergent quantum phenomena owing to its interplay with spin and photon degrees of freedom. In this work, a pair of chiral enantiomeric cocrystals were fabricated, where right-handed and left-handed cocrystals present significantly different spin polarization. The distinct chiral lattice structure predominantly accounts for the observed variations in magnetization; only the right-handed cocrystal undergoes a chiral inversion upon cooling. Due to the temperature-triggered chiral lattice structural phase transition, spin polarization of the right-handed cocrystal increases nonlinearly and rapidly with decreasing temperature. Moreover, the spin degeneracy lifting induced by the chiral lattice is also affected by chiral inversion, leading to a mirror response in the magnetic field control of circularly polarized transmittance. In addition, the phase transition temperature of the chiral lattice can be effectively tuned by circularly polarized light. Overall, this study provides deeper insight into the dynamic chiral lattice dependent spin and optics in homochiral cocrystals.