Intrinsic ferromagnetic coupling in Co{sub 3}O{sub 4} quantum dots activatedby graphene hybridization
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui (China)
Activating ferromagnetic couplings of transition-metallic ions in the antiferromagnetic metal oxide semiconductors is desired for creating ferromagnetic semiconductors for spintronics applications. Here, we report intrinsic ferromagnetic coupling in a typical antiferromagnetic metal oxide Co{sub 3}O{sub 4}, by virtue of a hybrid structure that modifies the valence state of Co ions. The Co{sub 3}O{sub 4} quantum dots exhibit ferromagnetism of 2.2 emu/g at 2 K after hybridization with reduced graphene oxide (RGO). In this hybrid structure, electron-transfer from RGO to Co{sub 3}O{sub 4} occurs and Co{sup 3+} ions occupying the octahedral (O{sub h}) positions are converted into Co{sup 2+}. Then the super-exchange interactions between Co{sup 2+} ions at T{sub d} (tetrahedral) and O{sub h} positions switch the magnetic coupling of Co{sup 2+}(T{sub d})–Co{sup 2+}(T{sub d}) from antiferromagnetic to ferromagnetic. These results offer promise for tailoring the spin exchange interactions of oxide semiconductors for spintronics applications.
- OSTI ID:
- 22590818
- Journal Information:
- Applied Physics Letters, Vol. 108, Issue 25; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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