Chiral Magneto-Optical Properties of Supra-Assembled Fe3O4Nanoparticles

Qysar Maqbool, Arum Jung, Sojeong Won, Jinhan Cho, Jeong Gon Son, Bongjun Yeom

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)54301-54307
Number of pages7
JournalACS Applied Materials and Interfaces
Volume13
Issue number45
DOIs
Publication statusPublished - 2021 Nov 17

Bibliographical note

Funding Information:
The authors acknowledge financial support from the National Research Foundation of Korea (NRF) grant funded by the Korea Government (Ministry of Science and ICT) (Nos. NRF-2021R1A2C4002523 and NRF-2019R1A4A1027627) and the Korea Institute of Science and Technology (KIST) Institutional Program (Project No. 2V08210). This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20202020800330).

Publisher Copyright:
© 2021 American Chemical Society.

Keywords

  • chirality
  • magnetic circular dichroism
  • magnetite
  • magneto-optical property
  • supra-assembly

ASJC Scopus subject areas

  • General Materials Science

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