10.1021/acs.nanolett.7b04866.s001
Sumin Lim
Sumin
Lim
Baeksoon Choi
Baeksoon
Choi
Sang Young Lee
Sang Young
Lee
Soonchil Lee
Soonchil
Lee
Ho-Hyun Nahm
Ho-Hyun
Nahm
Yong-Hyun Kim
Yong-Hyun
Kim
Taehun Kim
Taehun
Kim
Je-Geun Park
Je-Geun
Park
Jisoo Lee
Jisoo
Lee
Jaeyoung Hong
Jaeyoung
Hong
Soon Gu Kwon
Soon Gu
Kwon
Taeghwan Hyeon
Taeghwan
Hyeon
Microscopic States and the Verwey Transition of Magnetite
Nanocrystals Investigated by Nuclear Magnetic Resonance
American Chemical Society
2018
transition
NMR spectra changes
Magnetite Nanocrystals Investigated
nanocrystal size decreases
line width
7 μ m
Verwey
relaxation
distortion
Resonance 57 Fe
2018-02-20 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Microscopic_States_and_the_Verwey_Transition_of_Magnetite_Nanocrystals_Investigated_by_Nuclear_Magnetic_Resonance/5919484
<sup>57</sup>Fe 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.