Quantitative Measurements of Size-Dependent Magnetoelectric Coupling in Fe3O4 Nanoparticles

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• 作者：Kyongjun Yoo ; Byung-Gu Jeon ; Sae Hwan Chun ; Deepak Rajaram Patil ; Yong-jun Lim ; Seung-hyun Noh ; Jihyo Gil ; Jinwoo Cheon ; Kee Hoon Kim
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：16
• 期：12
• 页码：7408-7413
• 全文大小：428K
• ISSN：1530-6992

文摘

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 Fe₃O₄ nanoparticles have been enigmatic. We investigate quantitatively the ME coupling of spherical Fe₃O₄ nanoparticles 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 Fe₃O₄ nanoparticles 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.