title: Size Dependence of Metal-Insulator Transition in Stoichiometric Fe₃O4₄Nanocrystals.
abstract: Magnetite (Fe3O4) is one of the most actively studied materials with a famous metal-insulator transition (MIT), so-called the Verwey transition at around 123 K. Despite the recent progress in synthesis and characterization of Fe3O4 nanocrystals (NCs), it is still an open question how the Verwey transition changes on a nanometer scale. We herein report the systematic studies on size dependence of the Verwey transition of stoichiometric Fe3O4 NCs. We have successfully synthesized stoichiometric and uniform-sized Fe3O4 NCs with sizes ranging from 5 to 100 nm. These stoichiometric Fe3O4 NCs show the Verwey transition when they are characterized by conductance, magnetization, cryo-XRD, and heat capacity measurements. The Verwey transition is weakly size-dependent and becomes suppressed in NCs smaller than 20 nm before disappearing completely for less than 6 nm, which is a clear, yet highly interesting indication of a size effect of this well-known phenomena. Our current work will shed new light on this ages-old problem of Verwey transition.
authors.affiliation: †Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.|‡School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea.
authors.forename: Jisoo
authors.initials: J
authors.lastname: Lee
authors.affiliation: †Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.|‡School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea.
authors.forename: Soon Gu
authors.initials: SG
authors.lastname: Kwon
authors.affiliation: §Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 151-747, Korea.|∥Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
authors.forename: Je-Geun
authors.initials: JG
authors.lastname: Park
authors.affiliation: †Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 151-742, Korea.|‡School of Chemical and Biological Engineering, Seoul National University, Seoul 151-742, Korea.
authors.forename: Taeghwan
authors.initials: T
authors.lastname: Hyeon
keywords: Verwey transition; magnetic nanoparticle; magnetite nanocrystals; metal−insulator transition; size effect