Strain-Engineered Lattice-Driven Chirality in CsPbBr3 Nanorods.

This work demonstrates intrinsic lattice-driven chirality in CsPbBr3 nanorods, arising from strain-induced octahedral distortion, and fundamentally distinct from chiral-ligand-induced or molecule-driven chirality reported in most halide perovskites. The highly quantum-confined nanorods exhibit exceptionally large lattice strain nearly an order of magnitude higher than in previously reported systems which acts as the primary driving force for breaking local inversion symmetry. This strain-mediated symmetry breaking gives rise to strong circular dichroism (CD), natural circular dichroism (NCD), and robust polarization-dependent photoluminescence (PL), all persisting up to room temperature. Piezoresponse force microscopy confirms local ferroelectricity, magnetization measurement showed diamagnetic to superparamagnetic transition while magneto-optical measurements reveal nonlinear Zeeman response and zero-field magnetic signatures linked to the asymmetric chiral potential. Collectively, these results establish strain as a powerful route for inducing chirality, ferroelectricity, and magneto-optical coupling in achiral inorganic lattices, opening new pathways for chiral optoelectronics and spin-selective devices.