Wavelength-Selective Magneto-Optical Diodes Based on Rare-Earth Chiral Molecular Crystals

Chiral materials, integrating structural breaking of mirror-symmetry, exhibit physical properties that cannot be observed in centrosymmetric analogues. Among these properties, optical magneto-chiral anisotropy, the nonreciprocal absorption of light shown by chiral magnetized systems, is emerging as an enabling technology in magneto-optics and photonics. Here, we report on enantiopure chiral molecular crystals based on the erbium(III) rare-earth ion that display nonreciprocal, wavelength-selective, magnetic field-induced variations of the optical absorption coefficients up to ca. 200% for the intrashell f–f electronic transition falling in the 1.5 μm telecom wavelength range. Such a response is associated with an exceptionally high Magneto-Chiral Dichroism induced by the strong spin–orbit coupling of the Er(III) and the helical chirality at the lanthanide center, exalted by the magnetic-dipole-allowed character of the electronic transition. This chirality-induced nonreciprocal magneto-optical response represents a proof of concept for the use of these chiral crystalline molecular materials as potential components in magneto-optical diodes.