| NSF Org: |
DMR Division Of Materials Research |
| Recipient: |
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| Initial Amendment Date: | May 24, 2012 |
| Latest Amendment Date: | March 31, 2014 |
| Award Number: | 1202033 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Tomasz Durakiewicz
tdurakie@nsf.gov (703)292-4892 DMR Division Of Materials Research MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | June 1, 2012 |
| End Date: | May 31, 2016 (Estimated) |
| Total Intended Award Amount: | $345,000.00 |
| Total Awarded Amount to Date: | $345,000.00 |
| Funds Obligated to Date: |
FY 2013 = $110,000.00 FY 2014 = $110,000.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1523 UNION RD RM 207 GAINESVILLE FL US 32611-1941 (352)392-3516 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
FL US 32611-8440 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | CONDENSED MATTER PHYSICS |
| Primary Program Source: |
01001314DB NSF RESEARCH & RELATED ACTIVIT 01001415DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
****Technical Abstract****
This research explores the interplay between the electromagnetic and structural properties of cyanometallate coordination polymers. Specially, the fabrication of heterostructured films and particles increases the interface to bulk ratio, thereby allowing the stress/strain effects at the boundaries between the constituents to dominate the properties. Notably, irradiation with light allows persistent photocontrol of the magnetism up to liquid nitrogen temperatures, and this work seeks to explore different paths to extend this property to room temperature. In parallel, quantum spin chains will also be studied, and the emphasis is placed on S = 2 materials. The boundary between quantum and classical spins in one-dimension will be probed, and the influence of the anisotropy of the local magnetic environment will be explored. Both research thrusts will employ pressure as an external parameter, and these molecule-based magnets are significantly more pliable than their traditional solid-state counterparts. Physics and chemistry graduate students participate directly in every aspect of the research program and receive unique training in a variety of techniques, including magnetometry, X-ray and neutron scattering, and high-field, high-frequency magnetic resonance techniques. The tools are available in the local laboratories of the investigators or at national facilities like the National High Magnetic Field Laboratory (NHMFL), and the Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL).
****Non-Technical Abstract****
The discovery of novel phenomena and the development of new devices have now reached levels of maturity where increasingly complex materials are required as constituents of nanometer sized films and particles. Along this direction, molecule-based magnets are excellent materials because their properties can be tuned by synthesis protocols and controlled by external stimuli such as temperature, magnetic field, pressure/stress/strain, and irradiation by light. In this research program, materials historically generated as paint pigments are modified and employed in nanoscaled films and particles whose novel magnetic and optical properties can be externally controlled. The sensitive response results from stress and strain developed at the interface between the different constituents, and the nanometer length scales are required to diminish the static background that the bulk material contributes. The research seeks to extend this control to higher temperatures and in novel morphologies that can provide new magneto-optical switches and light harvesting devices. A variety of interdisciplinary tools, including magnetometry, electron microscopy, X-ray scattering, and magnetic resonance, are used to characterize the samples. Physics and chemistry graduate students are trained using state-of-the-art instrumentation and data analysis techniques, and undergraduate students are integrated into various aspects of the work. Ultimately, the goal is to increase the knowledge of the interplay between magnetic and electronic interactions in environmentally sensitive materials that are inexpensive to generate.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Intellectual Merit. The fundamental research funded by this grant improved the understanding of how visible light can control the global magnetic response of molecule-based heterostructures. Through a series of experiments, both components of the nano-scaled heterostructures were changed to demonstrate, for the first time, that the phenomenon is universal. The mechanism involves a thermally induced strain at the interface of the two components as the system is cooled. The required ingredients are a photo-active compound and an otherwise photo-inert, magnetic one. At low temperature, the irradiation by white light relaxes the thermally induced strain but places the interface domains of the ferromagnetic constituent in an anisotropic environment that causes the overall magnetic signal to decrease in low applied magnetic field. Equipped with this understanding, a new heterostructure was designed to demonstrate the photo-controlled magnetism above the technologically important temperature of liquid nitrogen (77 Kelvin). Ultimately, the photo-controlled magnetic state is relaxed at 125 Kelvin, but it could be extended to 200 Kelvin and above if a new photo-active component can be identified. A suite of experimental techniques were employed, including national laboratories providing access to high magnetic fields (National High Magnetic Field Laboratory), neutron scattering spectroscopy (High Flux Isotope Reactor and Spallation Neutron Source, Oak Ridge National Laboratory), and x-ray diffraction (Advanced Photon Source, Argonne National Laboratory). In addition, homemade pressure cells with optical access have been designed, constructed, and improved for use with a magnetometer.
Broader Impacts. The funding provided a means to train a diverse set of junior researchers. Specifically, graduate students in physics and chemistry at the University of Florida received interdisciplinary training, and after completing their PhD work, they secured employment in small and large technology companies in the United States. The undergraduate students used their experiences to guide their choices of continuing their training in graduate programs in science and engineering. All junior researchers participate in national or international meetings where they present their findings which are also disseminated in peer-reviewed journals. International collaborations with teams at P. J. Safarik University, Kosice, Slovakia, and Osaka University, Japan, provide expanded access to experimental and theoretical expertise while also enhancing the training environment for the junior researchers. Collaborations with two teams in chemistry departments that are primarily undergraduate programs (Eastern Washington University and the University of North Florida) have resulted in additional educational and training activities for both groups and peer-reviewed publications. Outreach activities to local schools include the diverse set of junior researchers who assist engaging students in hands-on demonstrations designed to enhance their understanding of science concepts while dispelling common misconceptions. The fundamental science of photo-controlled magnetism in nano-scaled heterostructures has the potential of providing a means of toggling spintronic devices.
Last Modified: 09/19/2016
Modified by: Mark W Meisel
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