  The chiral organic-inorganic halide perovskites (OIHPs) are vital candidates
for superior nonlinear optical (NLO) effects associated with circularly
polarized (CP) light. NLO in chiral materials often couples with magnetic
dipole (MD) transition, as well as the conventional electric dipole (ED)
transition. However, the importance of MD in NLO process of chiral OIHPs has
not yet been well recognized. Here, the analysis of second harmonic generation
circular dichroism (SHG-CD) provides the direct evidence that the MD
contribution leads to a large anisotropic response to CP lights in chiral
OIHPs, (R-/S-MBACl)2PbI4. The thin films exhibit great sensitivity to CP lights
over a wide wavelength range, and the g-value reaches up to 1.57 at the
wavelength where the contribution of MD is maximized. Furthermore, it is also
effective as CP light generator, outputting CP-SHG with maximum g-factor of
1.76 upon the stimulation of linearly polarized light. This study deepens the
understanding of the magneto-optical NLO processes in chiral systems.
