Achieving a high magnetization in sub-nanostructured magnetite films by spin-flipping of tetrahedral Fe3. cations  

作　　者：Tun Seng Herng Wen Xiao Sock Mui Poh Feizhou He Ronny Sutarto Xiaojian Zhu Runwei Li Xinmao Yin Caozheng Diao Yang Yang Xuelian Huang Xiaojiang Yu Yuan Ping Feng AndrivoRusydi Jun Ding 

机构地区：[1]Department of Materials Science and Engineering, National University of Singapore, 7 Engineering Drive I, Singapore 119260, Singapore [2]Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603, Singapore [3]NUSNNI-Nanocore, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore [4]Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore [5]Canadian Light Source, Saskatoon, Saskatchewan, S7N 2V3, Canada [6]Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Ningbo 31520 I, China

出　　处：《Nano Research》2015年第9期2935-2945,共11页纳米研究（英文版）

摘　　要：Magnetite Fe304 （ferrite） has attracted considerable interest for its exceptional physical properties： It is predicted to be a semimetallic ferromagnetic with a high Curie temperature, it displays a metal-insulator transition, and has potential oxide-electronics applications. Here, we fabricate a high-magnetization （〉 1 Tesla） high-resistance （-0.1 Ωcm） sub-nanostructured （grain size 〈 3 nm） Fe304 film via grain-size control and nano-engineering. We report a new phenomenon of spin- flipping of the valence-spin tetrahedral FeB＊ in the sub-nanostructured Fe304 film, which produces the high magnetization. Using soft X-ray magnetic circular dichroism and soft X-ray absorption, both at the Fe L3,2- and O K-edges, and supported by first-principles and charge-transfer multiple calculations, we observe an anomalous enhancement of double exchange, accompanied by a suppression of the superexchange interactions because of the spin-flipping mechanism via oxygen at the grain boundaries. Our result may open avenues for developing spin- manipulated giant magnetic Fe304-based compounds via nano-grain size control.

关 键 词：magnetite X—ray magnetic circulardichroism(XMCD) giant magnetization nanosuctured—Fe3O4 ferrite spin—flipping 

分 类 号：O[理学]