@article{Herng2015, 
author = {Tun Seng Herng and Wen Xiao and Sock Mui Poh and Feizhou He and Ronny Sutarto and Xiaojian Zhu and Runwei Li and Xinmao Yin and Caozheng Diao and Yang Yang and Xuelian Huang and Xiaojiang Yu and Yuan Ping Feng and Andrivo Rusydi and Jun Ding},
title = {Achieving a high magnetization in sub-nanostructured magnetite films by spin-flipping of tetrahedral Fe3+ cations},
year = {2015},
journal = {Nano Research},
volume = {8},
number = {9},
pages = {2935-2945},
keywords = {magnetite, X-ray magnetic circular dichroism (XMCD), giant magnetization, nanostructured-Fe3O4, ferrite, spin-flipping},
url = {https://www.sciopen.com/article/10.1007/s12274-015-0798-7},
doi = {10.1007/s12274-015-0798-7},
abstract = {Magnetite Fe3O4 (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 Ω·cm) sub-nanostructured (grain size < 3 nm) Fe3O4 film via grain-size control and nano-engineering. We report a new phenomenon of spin-flipping of the valence-spin tetrahedral Fe3+ in the sub-nanostructured Fe3O4 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 Fe3O4-based compounds via nano-grain size control.}
}