Researchers develop new methods to generate and improve magnetism of 2D materials

Florida State University researchers have unlocked a new way to produce a class of two-dimensional materials and enhance their magnetic properties. This work was published in Applied Chemistry.

Experimenting with metal magnets (called FGTs) made of the elements iron, germanium and tellurium, the research team achieved two breakthroughs: a collection method that produced 1,000 times more material than typical methods; and chemical modification. FGT magnetic capabilities.

“Two-dimensional materials are fascinating because of their chemistry, physics and potential uses,” said Michael Shatruk, a professor in the Department of Chemistry and Biochemistry who led the research. “We are working to develop more efficient Electronic devices that consume less power, are lighter, faster, and more responsive are an important part of this equation, but there is still a lot of work to be done to make them feasible.

The research began with liquid-phase exfoliation, a solution-processing technique that enables the mass production of two-dimensional nanosheets from layered crystals. The research team discovered that other chemists were using this method to synthesize two-dimensional semiconductors. They decided to apply it to magnetic materials.

Liquid-phase exfoliation allows chemists to collect larger amounts of these materials than more widespread mechanical exfoliation techniques that use tape during the collection process. In Shatruk’s case, researchers can collect 1,000 times more material through it than with mechanical stripping methods.

“This is a first step, and we found it to be very effective,” Shatruk said. “Once we did the exfoliation, we thought, ‘Well, exfoliation seems easy. What if we applied chemistry to these exfoliating nanosheets?'”

Their success in exfoliation produced enough FGT that could be used to further explore the material’s chemistry. The research team mixed the nanosheets with an organic compound called TCNQ (7,7,8,8-tetracyanoquinodimethane). This process creates a new material, FGT-TCNQ, by transferring electrons from FGT nanosheets to TCNQ molecules.

The new material is another breakthrough – permanent magnets with higher coercivity, a measure of a magnet’s ability to withstand external magnetic fields.

The best permanent magnets used in state-of-the-art technology can withstand magnetic fields of several Teslas, but achieving such resistance with 2D magnets such as FGTs is more challenging because the magnetic moments in the bulk material can almost flip. Negligible magnetic field – that is, the coercivity of the material is almost zero.

Exfoliating FGT crystals into nanosheets yielded a material with a coercivity of about 0.1 Tesla, which is not high enough for many applications. When FSU researchers added TCNQ to FGT nanosheets, they increased the coercivity to 0.5 Tesla, a five-fold increase, which is very promising for potential applications in 2D magnets, such as for spin filtering, Electromagnetic shielding or data storage.

Unlike electromagnets, which require electricity to maintain a magnetic field, permanent magnets have a long-lasting magnetic field of their own. They are key components in a variety of technologies such as MRI machines, hard drives, cell phones, wind turbines, speakers and other devices.

The researchers plan to explore the possibility of processing the material through other methods, such as through gas transport or stripping away molecular layers of TCNQ or similar active molecules and adding them to magnetic materials. They will also study how this processing affects other two-dimensional materials, such as semiconductors.

This is an exciting discovery because it opens many avenues for further exploration. Manipulated to enhance its functionality.

Co-authors of the Florida State University study include undergraduate Jaime Garcia-Oliver and faculty researcher Yan Xin. The collaborators from the University of Valencia in Spain are Professors Alberto M. Ruiz and José J. Baldoví.

This research was supported by the National Science Foundation.