Chiral mesostructured In2O3 films twisted with different crystal orientations

Abstract

Chiral mesostructured In2O3 films (CMIFs) composed of nanoflakes with exposed facets of (30-30) and (10-14) (referred to as CMIFs-30-30 and CMIFs-10-14) were synthesized using a malic acid (Mal)-assisted hydrothermal method, with or without the addition of trisodium citrate dihydrate as the structure directing agent. Density functional theory (DFT) calculations and molecular dynamics (MD) simulations suggest that the asymmetric displacement of In and O atoms generated by the chemical bonding of Mal on the crystal plane of as-prepared InOOH is the geometric basis for triggering the chiral distortion in the In2O3 crystal lattice and further hierarchical chirality in the CMIFs. After adding Na3C6H5O7ˑ2H2O, the preferential adsorption facet of Mal on InOOH crystal transforms from (0001) to (10-10) due to the stronger interaction between the Na3C6H5O7ˑ2H2O and the (0001) plane, arising from its multiple carboxyl groups. This results in different helical axes of nanoflakes in CMIFs-10-14 and CMIFs-30-30. Both CMIFs-30-30 and CMIFs-10-14 exhibit spin chiral anisotropy (SChA), with the manifestation of external magnetic field-independent but chirality-dependent asymmetric magnetic circular dichroism (MCD) due to the dominant contribution from chirality-induced effective magnetic fields when electrons move in a helical potential.