NSF-EAGER: Is Ferromagnetism an Intrinsic or Induced Property of Gold Nanoparticles?

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

TECHNICAL SUMMARY. Recent reports of ferromagnetism in gold nanoparticles are quite surprising since Au has completely filled 5d orbitals. Various explanations have been advanced to explain the unusual magnetic characteristics of nanostructured Au particles, but considerable controversy remains to this date regarding whether ferromagnetism is intrinsic or somehow related to the medium in which the particles are supported. In this effort, pulsed laser deposition (PLD) will be used to achieve dispersed Au nanoparticles with tight control of size and shape. PLD of Au in nonmagnetic oxide thin films (MgO, Al2O3, and ITO) is expected to provide simultaneous synthesis and in-situ passivation of the nanoparticles, while preventing agglomeration. The proposed experimental approach is expected to enable the synthesis of pristine Au nanoparticles for various characterization and physical property measurements. A thorough understanding of the origin of ferromagnetic behavior, if it truly exists in Au nanoparticles, is the expected outcome and will serve as a catalyst for the development of new theories to explain this surprising phenomenon. NON-TECHNICAL SUMMARY. The discovery that ferromagnetism is an intrinsic property of Au nanoparticles will be transformative, if confirmed, in the sense that is will revolutionize the current understanding of the physics of nanomagnetic materials. Ferromagnetism in Au nanoparticles, coupled with their already established unique optical properties, may have an enormous industrial impact, from data storage to biomedical applications. One graduate student will contribute to this research. Additionally, summer students will be participants in the outreach program, Success Through Enthusiasm and Awareness of Materials Engineering Research (Project STEAMER) at VPI.