Boosting Magnetic Properties of 2D Materials

Researchers from Florida State University have discovered a novel way to create a particular class of 2D material and enhance its magnetic characteristics. The journal Angewandte Chemie published the study.

2D materials, which are only a few atoms thick, offer exciting possibilities for new technologies that match the performance of current machines but on a microscopic scale.

In their experiments with FGT, a metallic magnet made of iron, germanium, and tellurium, the research team achieved two key breakthroughs. They successfully altered the magnetic properties of FGT through chemical treatment and developed a new method for collecting the material, which yielded 1,000 times more than traditional methods.

2D materials are really fascinating because of their chemistry, physics, and potential uses. We are moving toward developing more efficient electronic devices that consume less power, are lighter, faster, and more responsive. 2D materials are a big part of this equation, but there is still a lot of work to be done to make them viable. Our research is part of that effort.

Michael Shatruk, Study Research Lead and Professor, Department of Chemistry and Biochemistry, Florida State University

The study began with liquid phase exfoliation, a solution-processing method that creates large quantities of two-dimensional nanosheets from layered crystals. The research team noticed that other chemists used this technique to create 2D semiconductors, so they decided to use it with magnetic materials.

Chemists can gather significantly more of these materials using liquid phase exfoliation compared to the more commonly used mechanical exfoliation method, which involves tape. In their work, researchers were able to collect 1,000 times more material from Shatruk using this approach than they could with traditional mechanical exfoliation techniques.

That was the first step, and we found that it was pretty efficient. Once we did the exfoliation, we thought, Well, exfoliating things seems easy. What if we applied chemistry to these exfoliated nanosheets?

Michael Shatruk, Study Research Lead and Professor, Department of Chemistry and Biochemistry, Florida State University 

Their successful exfoliation process produced enough FGT to enable further research into the material’s chemistry. The team combined the FGT nanosheets with an organic compound called 7,7,8,8-Tetracyanoquinodimethane (TCNQ). This process moved electrons from the FGT nanosheets to the TCNQ molecules, resulting in a new material called FGT-TCNQ.

Another breakthrough was the creation of a permanent magnet with enhanced coercivity, a measure of a magnet’s resistance to external magnetic fields.

While the most advanced permanent magnets used in cutting-edge technologies can withstand magnetic fields of several Tesla, achieving similar resistance in 2D magnets like FGT is much more challenging. This is because the magnetic moment in bulk material can be reversed by a very weak field, meaning it has almost zero coercivity.

By exfoliating FGT crystals into nanosheets, the researchers created a material with a coercivity of about 0.1 Tesla—still not enough for many practical applications. However, when they added TCNQ to the FGT nanosheets, the coercivity increased fivefold to 0.5 Tesla. This opens up promising possibilities for using 2D magnets in areas like data storage, spin filtering, and electromagnetic shielding.

Unlike electromagnets, which require electricity to generate a magnetic field, permanent magnets generate a persistent magnetic field on their own. These magnets are crucial components in many technologies, including loudspeakers, wind turbines, cell phones, hard drives, and MRI machines.

Looking ahead, the researchers plan to explore alternative techniques, such as gas transport, to treat materials or exfoliate the TCNQ or similar molecules before adding them to the magnetic material. They’ll also investigate how these treatments could affect other 2D materials, like semiconductors.

It is an exciting finding because it opens up so many paths for further exploration. There are a lot of different molecules that can help stabilize 2D magnets, enabling the design of materials with multiple layers whose magnetic properties are manipulated to enhance their functionality.

Govind Sarang, Doctoral Candidate and Study Co-Author, Florida State University

The co-authors of the study include undergraduate student Jaime Garcia-Oliver and Faculty Researcher Yan Xin. Collaborators from the University of Valencia, Spain, were Alberto M. Ruiz and Professor José J. Baldoví.

The National Science Foundation funded the study.

Journal Reference:

‌Sasi Kumar, G., et al. (2024) Opening the Hysteresis Loop in Ferromagnetic Fe₃GeTe₂ Nanosheets Through Functionalization with TCNQ Molecules. Angewandte Chemie International Edition. doi.org/10.1002/anie.202412425.