Maqbool, Q. Jung, Arum Won, Sojeong Cho, Jinhan Son, Jeong Gon Yeom, Bongjun 2024-01-19T13:31:37Z 2024-01-19T13:31:37Z 2022-01-10 2021-11 1944-8244 https://pubs.kist.re.kr/handle/201004/116188 Research on the chiral magneto-optical properties of inorganic nanomaterials has enabled novel applications in advanced optical and electronic devices. However, the corresponding chiral magneto-optical responses have only been studied under strong magnetic fields of ≥1 T, which limits the wider application of these novel materials. In this paper, we report on the enhanced chiral magneto-optical activity of supra-assembled Fe3O4 magnetite nanoparticles in the visible range at weak magnetic fields of 1.5 mT. The spherical supra-assembled particles with a diameter of ∼90 nm prepared by solvothermal synthesis had single-crystal-like structures, which resulted from the oriented attachment of nanograins. They exhibited superparamagnetic behavior even with a relatively large supraparticle diameter that exceeded the size limit for superparamagnetism. This can be attributed to the small size of nanograins with a diameter of ∼12 nm that constitute the suprastructured particles. Magnetic circular dichroism (MCD) measurements at magnetic fields of 1.5 mT showed distinct chiral magneto-optical activity from charge transfer transitions of magnetite in the visible range. For the supraparticles with lower crystallinity, the MCD peaks in the 250-550 nm range assigned as the ligand-to-metal charge transfer (LMCT) and the inter-sublattice charge transfer (ISCT) show increased intensities in comparison to those with higher crystallinity samples. On the contrary, the higher crystallinity sample shows higher MCD intensities near 600-700 nm for the intervalence charge transfer (IVCT) transition. The differences in MCD responses can be attributed to the crystallinity determined by the reaction time, lattice distortion near grain boundaries of the constituent nanocrystals, and dipolar interactions in the supra-assembled structures. ？ 2021 American Chemical Society. English American Chemical Society Chiral Magneto-Optical Properties of Supra-Assembled Fe3O4Nanoparticles Article 10.1021/acsami.1c16954 1 ACS Applied Materials & Interfaces, v.13, no.45, pp.54301 - 54307 ACS Applied Materials & Interfaces 13 45 54301 54307 N scie scopus 000726619200006 2-s2.0-85119418935 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Science & Technology - Other Topics Materials Science Article chirality magnetic circular dichroism magnetite magneto-optical property supra-assembly