The MIT team showed that when two monolithic TMDs (each with only a few atomic layers) are stacked in parallel with each other, the material will become a ferroelectric. In ferroelectric materials, positive and negative charges spontaneously flow to different sides or magnetic poles. When an external electric field is applied, these charges will be converted to both sides, thus reversing polarization. In new materials, all this happens at room temperature.
TMDs is widely known for its electrical and optical properties. Researchers believe that the interaction between these characteristics and newly endowed ferroelectricity may lead to various interesting applications.
Pablo Jalillo-herrero of Cecil said: "In a very short time, we have succeeded in greatly expanding the small and growing family of two-dimensional ferroelectrics, which are the key materials at the forefront of nanoelectronics and artificial intelligence applications." Ida Green, a professor of physics and the leader of this work, was published in the journal Nature Nanotechnology. Jarillo herrero is also a member of the Materials Research Laboratory of the Massachusetts Institute of Technology.
In addition to Jarillo herrero, the author of the paper is Wang, a graduate student in physics at MIT. Ann Tian Jian II and Xi Zhang, postdoctoral fellows at MIT; Liu Song of Columbia University; Ken Watanabe and Takashi Taniguchi; Japan National Institute of Materials Science; James Horn of Columbia University and Fu Liang, associate professor of physics at MIT. (The picture above shows Ann Tian Jian II (left), a postdoctoral assistant at MIT, and Wang, a physics graduate student at MIT, in the MIT laboratory).
Ultrathin ferroelectric
Last year, Jalilo Herrero and many of his colleagues proved that when two atomic thin boron nitride (BN) sheets are stacked in parallel with each other, BN becomes a ferroelectric. In the present work, researchers apply the same technology to TMD.
Ultrathin ferroelectrics made of BN and TMD may have important applications, including more dense computer memory storage. But they are rare. With the addition of four new TMD ferroelectrics reported in Nature Nanotechnology, they all belong to the same semiconductor family. "The number of ultrathin ferroelectrics has almost doubled at room temperature," Wang said. In addition, she pointed out that most ferroelectric materials are insulators. "Few ferroelectrics are semiconductors."
"This is not limited to BN and TMD," said Ann Tian Jian II. "We hope that our technology can be used to add ferroelectricity to other existing materials. For example, can you add ferroelectricity to magnetic materials? "
This work was funded by the Science Office of the U.S. Department of Energy, the Army Research Office, the Gordon and Betty Moore Foundation, the National Science Foundation, the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) and the Japan Association for the Promotion of Learning.
involve
Wang, X, An Tian, K, Zhang, Y, et al., "Interface Ferroelectricity of Bitransition Metal Disulfide Pyramid Stacking"; Nate. Nanotechnology. (2022).