Microscopic States and the Verwey Transition of Magnetite Nanocrystals Investigated by Nuclear Magnetic Resonance

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Title
Microscopic States and the Verwey Transition of Magnetite Nanocrystals Investigated by Nuclear Magnetic Resonance
Author(s)
Sumin Lim; Baeksoon Choi; Sang Young Lee; Soonchil Lee; Ho-Hyun Nahm; Yong-Hyun Kim; Taehun Kim; Je-Geun Park; Jisoo Lee; Jaeyoung Hong; Soon Gu Kwon; Taeghwan Hyeon
Publication Date
2018-03
Journal
NANO LETTERS, v.18, no.3, pp.1745 - 1750
Publisher
AMER CHEMICAL SOC
Abstract
57Fe nuclear magnetic resonance (NMR) of magnetite nanocrystals ranging in size from 7 nm to 7 μm is measured. The line width of the NMR spectra changes drastically around 120 K, showing microscopic evidence of the Verwey transition. In the region above the transition temperature, the line width of the spectrum increases and the spin-spin relaxation time decreases as the nanocrystal size decreases. The line-width broadening indicates the significant deformation of magnetic structure and reduction of charge order compared to bulk crystals, even when the structural distortion is unobservable. The reduction of the spin-spin relaxation time is attributed to the suppressed polaron hopping conductivity in ferromagnetic metals, which is a consequence of the enhanced electron-phonon coupling in the quantum-confinement regime. Our results show that the magnetic distortion occurs in the entire nanocrystal and does not comply with the simple model of the core-shell binary structure with a sharp boundary. © 2018 American Chemical Society
URI
https://pr.ibs.re.kr/handle/8788114/4645
ISSN
1530-6984
Appears in Collections:
Center for Nanoparticle Research(나노입자 연구단) > Journal Papers (저널논문)
Center for Correlated Electron Systems(강상관계 물질 연구단) > Journal Papers (저널논문)
Files in This Item:
2018-243_(사사없음)Microscopic States and the Verwey Transition of Magnetite Nanocrystals Investigated by Nuclear Magnetic Resonance.pdfDownload

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