Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing
Self-assembly of multicomponent nanocrystal superlattices provides a modular approach to the design of metamaterials by choosing constituent nanocrystal building blocks with desired physical properties and engineering the interparticle coupling. In this work, we report the self-assembly of binary nanocrystal superlattices composed of magnetically hard CoFe2O4 nanocrystals and magnetically soft Fe3O4 nanocrystals. Both NaZn13- and MgZn2-type CoFe2O4-Fe3O4 binary nanocrystal superlattices have been formed by the liquid-air interfacial assembly approach. Exchange coupling is achieved in both types of binary superlattices after thermal annealing under vacuum at 400 degrees C. The exchange-coupled CoFe2O4-Fe3O4 binary nanocrystal superlattices show single-phase magnetization switching behavior and magnetoresistance switching behavior below 200 K. The NaZn13-type CoFe2O4-Fe3O4 binary nanocrystal superlattices annealed at 500 degrees C even exhibit bistable magnetoresistance switching behavior at room temperature constituting a simple nonvolatile memory function.
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- DOE Contract Number:
- DE-AR0000123
- OSTI ID:
- 1211204
- Journal Information:
- ACS Nano, Vol. 7, Issue 2; ISSN 1936-0851
- Country of Publication:
- United States
- Language:
- English
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