On the last January 19, the Science published an article called “nanoparticles and gyromagnetic gels” and is the result of a joint project of 3 years between a University of Michigan (EUA) and Federal University of San Carlos (UFSCar – Brazil) on a discovery of a nanoparticle compound of cobalt oxide synthesized in the presence of amino acid L-cysteine, which in theory is capable of rendering a material invisible and cheap technologies like holography.
Holography technologies could already be used using magnetic fields to change the path of light, but the materials that can do this are expensive, fragile, and opaque. Some only work in temperatures as cold as the vacuum of space. Now researchers at the University of Michigan and the Federal University of São Carlos in Brazil have demonstrated that low-cost nanoparticles in a gel can replace traditional materials at a dramatically reduced cost. And his approach works at room temperature.
It opens up a world of possibilities for the use of magnetic fields to modulate light, with applications in autonomous vehicle sensors, space communication and wireless optical networks.
André Faria de Moura is a professor at the Department of Chemistry of the Federal University of São Carlos (DQ-UFSCar) and researcher at the Center for the Development of Functional Materials (CDMF-CEPID-FAPESP). According to Moura, “Controlling the magnetism and a chirality of a material of the researchers managed to make it transparent. The interaction of light with matter is one of the main operations to convey, to store both energy and information, to increase our control over these interactions, and the great goal of nanotechnology, and we have already produced a good part of the goal, controlling the form and the size of these particles and their chemical composition. This article presents the simultaneous use of magnetism and chirality of the material as a much finer form of control as that light interacts with matter, either making the material transparent or increasing its absorption We are inaugurating a new research line with a lot of potential applications including … 3D visualization and holography in real time.” The other authors of the article are Jihyeon Yeom, Uallisson S. Santos, Mahshid Chekini, Minjeong Cha and Nicholas A. Kotov.
To date, expensive rare-earth metals such as europium, cerium and yttrium have been used to demonstrate how the path, speed and intensity of optical, or light-based, signals can be controlled with magnetic fields. This capability is already in commercial use in high-speed fiber optic internet cables. But the elements’ cost and temperature needs have kept the technology from greater use.
A cost-effective, room temperature solution to magnetic control of twisted light could enable mass-market 3-D displays, holographic projectors and new generation of Light Detection and Ranging (LIDAR). LIDAR is one of the main technologies that give “sight” to autonomous vehicles.
“Many companies and labs developed exciting prototypes using magneto-optic technology,” said Nicholas Kotov, U-M’s Florence V. Cejka Professor of Chemical Engineering, who led the project. “But their technological acceptance has been limited to date because of the fundamental materials issues with rare earth magneto-optics. It has been like trying to solve the Rubik’s Cube puzzle. You get one property right but lose the others.” Kotov is also a professor of materials science and engineering.
The group of researchers have created a cobalt-based chiromagnetic nanoparticle that could enable more widespread use of light modulation via magnetism. The researchers demonstrate that they could use nanoparticles based on inexpensive cobalt oxide—a white-colored, magnetic semiconductor—to control twisted light well using magnetic fields. The trick, the researchers found, was to twist the nanoparticles themselves by coating them with amino acids. The twist could be either right- or left-handed—a property called chirality.
The chirality of the nanoparticles produced a heightened sensitivity to magnetism and also strengthened interactions with twisted light—more formally referred to as “circularly polarized light.” The researchers demonstrated that by suspending the nanoparticles in a transparent, elastic, room-temperature gel, they could change the intensity of circularly polarized light by applying a magnetic field.
“This opens the road to the wide proliferation of magneto-optical devices with exciting possibilities emerging in 3-D displays and real-time holography—all utilizing circularly-polarized light,” Kotov said. “Furthermore, the small size of the nanoparticles enables their use in computer engineering and large-scale manufacturing of magneto-optical composites.”
Using the Brazilian supercomputer SDumont, scientists have demonstrated where and how cysteine molecules bind to nanoparticles of cobalt oxide, how these structures vibrate and move, and how electrons reorganize when light is absorbed. According to Moura, this still does not make the material really invisible, properly, but shows that they are headed in the right direction. “Following on the research, we hope to form a library of various chiral nanoparticles, which will be used as assembly blocks for larger and more complex structures, with even greater control of the interaction of the material with light. both in the synthesis and experimental characterization of the new materials, and in the computational modeling of its properties and functionalities, “he explained.
The research is funded by the National Science Foundation and the Air Force Office of Scientific Research in the U.S. and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Fundação de Amparo à Pesquisa do Estado de São Paulo in Brazil. U-M is pursuing patent protection for the intellectual property and is seeking commercialization partners to help bring the technology to market.
Now let’s hope this technology gets to market soon! Who knows in a few years we will not be talking through holograms?
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