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.