Researchers have developed an innovative method for creating a particular type of 2D material while enhancing its magnetic properties.
With a thickness of only a few atoms, 2D materials offer transformative potential for new technologies that are compact yet possess the same functions as current machines.
At Florida State University, scientists have discovered a novel approach to producing a specific type of 2D material and enhancing its magnetic characteristics. Their findings were published in Angewandte Chemie.
The team explored a metallic magnet comprised of iron, germanium, and tellurium, known as FGT. They achieved two significant advancements: a method to collect 1,000 times more material compared to conventional methods, and the capacity to modify FGT’s magnetic features via a chemical treatment.
“2D materials are incredibly intriguing due to their chemistry, physics, and potential applications,” remarked Michael Shatruk, a professor in the Department of Chemistry and Biochemistry and the lead on this research. “Our goal is to create more efficient electronic devices that use less energy, are lighter, faster, and more responsive. 2D materials play a crucial role in this, but there is still much work needed to improve their feasibility. Our research contributes to that goal.”
The research began with liquid phase exfoliation, a technique that produces 2D nanosheets from layered crystals in large quantities. The team observed that other chemists were using this method for synthesizing 2D semiconductors and chose to apply it to magnetic materials.
Liquid phase exfoliation enables chemists to gather far more of these materials than traditional mechanical exfoliation methods, which often use tape. In Shatruk’s study, this method allowed the researchers to collect 1,000 times more material than what mechanical exfoliation could achieve.
“This was the initial step, and we found it quite effective,” Shatruk explained. “After achieving exfoliation, we thought, ‘What if we introduced chemistry to these exfoliated nanosheets?'”
Their success in exfoliating produced sufficient FGT for further study into its chemistry. The team combined the nanosheets with an organic compound known as TCNQ, or 7,7,8,8-Tetracyanoquinodimethane, resulting in a new material called FGT-TCNQ, created through the transfer of electrons from the FGT nanosheets to the TCNQ molecules.
This new material represented another breakthrough—a permanent magnet with increased coercivity, which measures a magnet’s resistance to external magnetic fields.
While advanced permanent magnets used in cutting-edge technologies can endure magnetic fields of several Tesla, achieving similar resistance with 2D magnets like FGT poses significant challenges. This is because the magnetic moment in bulk materials can be reversed with a very slight field, meaning they have nearly zero coercivity.
By exfoliating FGT crystals into nanosheets, the material exhibited a coercivity of roughly 0.1 Tesla, which is insufficient for many applications. However, when the FSU team incorporated TCNQ with the FGT nanosheets, they raised the coercivity to 0.5 Tesla—a five-fold increase, which is very promising for possible uses of 2D magnets in spin filtering, electromagnetic shielding, or data storage.
Permanent magnets differ from electromagnets in that they maintain a magnetic field independently without requiring electricity. They are essential components in various technologies, including MRI machines, hard drives, smartphones, wind turbines, loudspeakers, and more.
The researchers plan to investigate additional treatment methods, such as gas transport or exfoliating the molecular layer of TCNQ or similar active molecules for integration with the magnetic material. They will also explore how such treatments may impact other 2D materials, including semiconductors.
“This finding is exciting because it paves the way for numerous avenues for future research,” stated Govind Sarang, a doctoral candidate and co-author of the study. “Many different molecules may help stabilize 2D magnets, allowing for the design of multi-layered materials which can have their magnetic properties adjusted to enhance functionality.”
The co-authors from FSU included undergraduate student Jaime Garcia-Oliver and faculty researcher Yan Xin. Collaborators from the University of Valencia, Spain, included Alberto M. Ruiz and Professor José J. Baldoví.
This research received funding from the National Science Foundation.