题目：Nano-Watermelon：Synthesis and Magnetism

报告人：Prof. You Qiang (强游)

        Physics Department, University of Idaho, Moscow ID 83844-0903. (美国爱达荷大学)

时间：7月7日（周一） 上午 10：00

地点：李薰楼468室

摘要：

This research investigated novel core-shell magnetic nanoparticles (NPs) with unique nanostructures and magnetic properties. Understanding the fundamental physics of antiferromagnetic - ferromagnetic interactions is essential to apply in different applications. Chromium (Cr) doped and undoped core-shell iron/iron-oxide NPs have been synthesized using cluster deposition system and studied with respect to their nanostructures, morphologies, sizes, chemical composition and magnetic properties. The room-temperature magnetic properties of Fe based NPs shows the strong dependence of intra/inter-particle interaction on NP size. The Cr-doped Fe NP shows the origin of sigma-FeCr phase at very low Cr concentration (2 at.%) unlike others reported at high Cr content and interaction reversal from dipolar to exchange interaction. A theoretical model of watermelon NPs is constructed based on the experimental results and core-shell NP system in order to explain the physics of exchange interaction in Cr-doped MNPs.

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