Physicists design new properties from “white” graphene

Researchers at MIT are reporting the creation of new ultra-thin materials with ferroelectricity. This is a property that can give materials important applications such as computer memory. Here, Kenji Yasuda (left), a postdoctoral researcher at MIT, and Xirui Wang, a graduate student in physics at MIT, hold the key to the MIT Lab. Credits: Kenji Yasuda and King Xirui

Ultra-thin materials made of a single layer of atoms have attracted the attention of scientists since the discovery of the first such material, graphene, about 17 years ago. Among the advances since then, researchers, including researchers in MIT’s pioneering labs, have been new by stacking individual sheets of 2D material and sometimes twisting them at small angles, from superconductivity to magnetism. I have discovered that it can give properties.

Today, MIT physicists and colleagues in the same lab are doing just that. Boron nitrideIt is known as “white graphene” because it has a similar atomic structure to that it is not famous.The team has two single sheets of boron Nitride When stacked parallel to each other, the material becomes a ferroelectric substance, and the positive and negative charges of the material spontaneously go to different sides or poles. When an external electric field is applied, these charges switch sides and reverse polarization. Importantly, this all happens at room temperature.

New materials that work through a mechanism that is completely different from existing ferroelectric materials can have many uses.

“Various physical properties have already been discovered in different 2D materials. Now you can easily stack ferroelectric boron nitride with other material families to create emergent properties and new features.” , Says Pablo Jarillo-Herrero, Professor of Cecil and Ida Green. Of physics and work leaders reported in the journal Science. Jarillo-Herrero is also affiliated with MIT’s Materials Laboratory.

In addition to Jarillo-Herrero, the additional author of this treatise is Kenji Yasuda, a postdoctoral fellow at MIT. King Xirui of the Graduate School of Physics, Massachusetts Institute of Technology, and Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science.

Potential applications

Among the potential applications of new ultra-thin ferroelectric materials, “one exciting possibility is to use it for higher density memory storage,” said Yasuda, lead author of Science Paper. I am. This is because by switching the polarization of the material, 1s and 0s (digital information) can be encoded, and that information stabilizes over time. It does not change unless an electric field is applied. In a scientific treatise, the team reports a proof-of-concept experiment showing this stability.

The new material is only one billionth of a meter thick and is one of the thinnest ferroelectrics ever manufactured, allowing for even higher density computer memory storage. ..

The team also discovered that twisting parallel sheets of boron nitride at a slight angle to each other creates yet another “all-new type of ferroelectric state,” Yasuda says. This popular approach, known as twistronics, was pioneered by the Jarillo-Herrero group, who used it to achieve unconventional superconductivity in graphene.

New physics

The new ultra-thin ferroelectric material is exciting because it involves new physics.The mechanism behind how it works is completely different from the traditional one Ferroelectric material..

“Out-of-plane ferroelectric switching is caused by in-plane sliding motion between two boron nitride sheets. This unique bond between vertical polarization and horizontal motion is the lateral direction of boron nitride. Rigidity makes it possible. “

Towards other ferroelectrics

Yasuda states that other new ferroelectrics can be manufactured using the same techniques described in Science. “The method of converting a non-ferroelectric starting material to an ultra-thin ferroelectric can be applied to other materials with an atomic structure similar to boron nitride, greatly expanding the family of ferroelectrics. Currently, there are very few ultrathin ferroelectrics, “he says. Researchers are currently working on that goal with some promising results.

Jarillo-Herrero Lab is a pioneer in manipulating and exploring ultra-thin 2D materials such as graphene.Nevertheless, ultra-thin conversion boron The conversion from nitrides to ferroelectrics was unexpected.

Xirui Wang says:

“I still remember seeing anomalous jumps in my data when I was making measurements. I decided to run the experiment again. When I ran it many times, something new happened. I confirmed that it was. ”

Newly discovered graphene properties can impact next-generation computing

For more information:
Kenji Yasuda et al., Ferroelectricity due to lamination engineering of double-layer boron nitride, Chemistry (2021). DOI: 10.1126 / science.abd3230

Quote: Physicist obtained “white” graphene from on September 7, 2021 (September 7, 2021) Design new properties from

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Physicists design new properties from “white” graphene

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