Achieving a high magnetization in sub-nanostructured magnetite films by spin-flipping of tetrahedral Fe3+ cations
- 179 Downloads
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.
Keywordsmagnetite X-ray magnetic circular dichroism (XMCD) giant magnetization nanostructured-Fe3O4 ferrite spin-flipping
Unable to display preview. Download preview PDF.
- Smith, J.; Wijn, H. P. J. Ferrites; Philips’ Technical Library: Eindhoven, Holland, 1959.Google Scholar
- Stöhr, J.; Siegmann, H. C. Magnetism: From fundamentals to nanoscale dynamics; Springer-Verlag: Berlin, 2006.Google Scholar