title: Quantitative Measurements of Size-Dependent Magnetoelectric Coupling in Fe3O4Nanoparticles.
abstract: Bulk magnetite (Fe3O4), the loadstone used in magnetic compasses, has been known to exhibit magnetoelectric (ME) properties below ∼10 K; however, corresponding ME effects in Fe3O4nanoparticles have been enigmatic. We investigate quantitatively the ME coupling of spherical Fe3O4nanoparticles with uniform diameters (d) from 3 to 15 nm embedded in an insulating host, using a sensitive ME susceptometer. The intrinsic ME susceptibility (MES) of the Fe3O4nanoparticles is measured, exhibiting a maximum value of ∼0.6 ps/m at 5 K for d = 15 nm. We found that the MES is reduced with reduced d but remains finite until d = ∼5 nm, which is close to the critical thickness for observing the Verwey transition. Moreover, with reduced diameter the critical temperature below which the MES becomes conspicuous increased systematically from 9.8 K in the bulk to 19.7 K in the nanoparticles with d = 7 nm, reflecting the core-shell effect on the ME properties. These results point to a new pathway for investigating ME effect in various nanomaterials.
authors: Center for Novel States of Complex Materials Research and Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University , Seoul 151-747, South Korea.
authors: Kyongjun
authors: K
authors: Yoo
authors: Center for Novel States of Complex Materials Research and Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University , Seoul 151-747, South Korea.
authors: Byung-Gu
authors: BG
authors: Jeon
authors: Center for Novel States of Complex Materials Research and Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University , Seoul 151-747, South Korea.
authors: Sae Hwan
authors: SH
authors: Chun
authors: Center for Novel States of Complex Materials Research and Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University , Seoul 151-747, South Korea.
authors: Deepak Rajaram
authors: DR
authors: Patil
authors: Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, South Korea.
authors: Yong-Jun
authors: YJ
authors: Lim
authors: Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, South Korea.
authors: Seung-Hyun
authors: SH
authors: Noh
authors: Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, South Korea.
authors: Jihyo
authors: J
authors: Gil
authors: Center for Nanomedicine, Institute for Basic Science (IBS) , Seoul 03722, South Korea.
authors: Jinwoo
authors: J
authors: Cheon
authors: Center for Novel States of Complex Materials Research and Institute of Applied Physics, Department of Physics and Astronomy, Seoul National University , Seoul 151-747, South Korea.
authors: Kee Hoon
authors: KH
authors: Kim
keywords: Magnetoelectric; iron oxide; magnetic nanoparticle; magnetite nanoparticle; size effect