1. Large, Negative Magnetoresistance in an Oleic Acid-Coated Fe3O4 Nanocrystal Self-Assembled Film
- Author
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Department of Materials Science, Kyushu Institute of Technology, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Kohiki, Shigemi, Kinoshita, Tomoki, Nara, Koichiro, Akiyama-Hasegawa, Kotone, Mitome, Masanori, Department of Materials Science, Kyushu Institute of Technology, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Kohiki, Shigemi, Kinoshita, Tomoki, Nara, Koichiro, Akiyama-Hasegawa, Kotone, and Mitome, Masanori
- Abstract
type:Journal Article, An oleic acid-coated Fe3O4 nanocrystal self-assembled film was fabricated via drop casting of colloidal particles on a SiO2/Si substrate. The film exhibited bifurcation of the zero-field-cooled and field-cooled magnetizations around 250 K. The nonlinear current-voltage (I–V) characteristics between the source and drain electrodes in both zero and non-zero magnetic fields (H) were observed above and below the bifurcation temperature. A large negative magnetoresistance (MR ≈ −60%) was achieved at 200 K and H = 1 T. Even at 295 K and 0.2 T, the negative MR (≈ −50%) persisted. A Fowler–Nordheim plot and power-law scaling of the I–V characteristics revealed that the current flows through two-dimensional (2D) percolated electron tunneling paths. The enlargement of MR can be attributed to spin-dependent electron tunneling between magnetically coupled Fe3O4 nanocrystals self-assembled in 2D ordered arrays.
- Published
- 2017