# Presentation: 182109

## Sequential Assembly of Magnetic Prussian Blue 

- Photo-induced magnetism is controlled by the orientation of the film.

**Sequential Assembly of Magnetic Prussian Blue **
**Thin Films with Photo-Induced Magnetism**

- Young D. Huh, Franz Frye, Sarah Lane, Daniel R. Talham, Chemistry, Univ. of Florida

*Applied Physics Letters* _85_ (2005) 3797-3799.
- Supported by NSF DMR-0305371,
- NSF DGE-0209410, and NSF DMR-0113714.

- Ju-Hyun Park, Erik Čižmár, and Mark W. Meisel, Physics, University of Florida

- The anisotropic photo-induced** **magnetization depends on the relative strength of dipolar field (**H****D**) produced by primordial  spins compared to the external magnetic field (**H****E**).

- RbjCok[Fe(CN)6]l·nH2O

- New thin-film magnets based on Prussian blue analogs were generated and discovered to possess unusual anisotropic photo-induced** **magnetism.

**Notes:**
	The first artificially manufactured color was Prussian blue, which was discovered by Diesbach of Berlin in about 1704.  Today, one interesting use of Prussian blue is the removal of select radioactive materials from people’s bodies, but must be taken under the guidance of the Radiation Emergency Assistance Center/Training Site (REAC/TS) of the Oak Ridge Institute.
	Prussian blue is made from iron ions that exist in two different electronic configurations due to the network that they form with carbon-nitrogen atoms.  In 1996, Sato and coworkers were the first to identify photo-induced magnetism in a Prussian blue analog, which contained cobalt and iron instead of simply iron.  When these powdered samples were cooled from room temperature down to liquid helium temperatures (4 Kelvin), some of the ions exchanged electrons and went into a non-magnetic state.  When light irradiated the sample at low temperatures, the photons caused the electrons to transfer from one ion to another, causing the re-emergence of the magnetic state found at room temperature.
	Using novel fabrication techniques, we have been able to fabricate Prussian blue analog materials in thin films.  We have observed the photo-induced magnetism first reported by Sato and coworkers; however, we also discovered an unexpected anisotropic effect that depends of the orientation of the film with the applied external magnetic field.  This novel anisotropy is controlled by our fabrication methods and affords optical and orientational control of the magnetic properties of the film.  These properties have potential applications in new magnetic switches and memory devices.

## Sequential Assembly of Magnetic Prussian Blue 

**Social Impact**
- The combined physics/chemistry studies perform molecular-level manipulation leading to new solid-state structures.  This “bottom-up” approach yielded a new nano-sized magnetic thin-film possessing unusual photo-induced magnetism.  This exotic functionality is optically and orientationally controlled and provides an prototype for new magnetic devices.

**Education**
- This work was conducted as a close collaboration between physics and chemistry groups that are dedicated to the training of young researchers.  Three graduate students (Park, Frye, and Lane) and two international scholars (Huh, South Korea, and Čižmár, Slovakia) played key roles in the research.  Erik Čižmár’s participation was made possible by a NSF-NATO Postdoctoral Fellowship (DGE-0209410).  The young researchers receive interdisciplinary training that includes expertise in SQUID magnetometry made possible by NSF DMR-0113714.

**Sequential Assembly of Magnetic Prussian Blue **
**Thin Films with Photo-Induced Magnetism**

-  Young D. Huh, Franz Frye, Sarah Lane, Daniel R. Talham, Chemistry, Univ. of Florida

*Applied Physics Letters* _85_ (2005) 3797-3799.
- Supported by NSF DMR-0305371,
- NSF DGE-0209410, and NSF DMR-0113714.

- Ju-Hyun Park, Erik Čižmár, and Mark W. Meisel, Physics, University of Florida

**Notes:**
	Today, scientific research is often interdisciplinary in nature, and our work is no exception.  Our team consists of physicists and chemists working in concert to generate and to characterize new materials.  As a result, the students learn how both physicists and chemists, often using different jargon, discuss the same topics, and magnetism is our primary example.  In addition, our work involves international collaborators who share their expertise with us and study approaches that we have developed.  Without a doubt, technological progress is accelerated by this free exchange of ideas, and in parallel, each participant experiences an increased sense of cultural awareness that increases the understanding of societies from different parts of the world.