Researchers from City University of Hong Kong (CityUHK) and local collaborators have identified a new vortex electric field that could significantly improve future electronic, magnetic, and optical devices.
Recently, researchers from City University of Hong Kong (CityUHK) and their local partners discovered a novel vortex electric field that holds promise for improving future electronic, magnetic, and optical devices.
The study, published in Science, is notable because it could enhance the performance of various devices, particularly by improving memory reliability and processing speeds. With additional research, this discovery could influence sectors like quantum computing, spintronics, and nanotechnology.
“In the past, creating a vortex electric field necessitated costly thin-film deposition methods and elaborate processes. However, our findings show that a straightforward twist of bilayer 2D materials can easily generate this vortex electric field,” explained Professor Ly Thuc Hue, from the Department of Chemistry and a key member of the Centre of Super-Diamond and Advanced Films at CityUHK.
Selecting a clean interface usually involves directly synthesizing bilayers. Maintaining flexibility in the twisting angles, especially for low-angle twists, can be challenging. Professor Ly’s team developed a pioneering ice-assisted transfer technique, which was essential in achieving a clean interface, thus enabling the manipulation and creation of twisted bilayers with ease.
While existing research mainly focused on twists smaller than 3 degrees, this team’s method allowed them to produce a wide range of twist angles from 0 to 60 degrees, using a combination of synthesis and artificial stacking via ice-assisted transfer.
Versatile Applications
The discovery of a new vortex electric field within the twisted bilayer has resulted in the formation of a 2D quasicrystal, which could improve future electronic, magnetic, and optical devices. Quasicrystals are highly sought after because of their irregular structures, which offer low thermal and electrical conductivity, making them ideal for durable surface coatings, such as those used on frying pans.
According to Professor Ly, these structures have a wide range of potential applications, as the generated vortex electric field varies with the twist angle. Quasicrystals may enhance memory stability in electronic devices, increase processing speed, enable lossless polarization switching, generate unique optical effects, and advance spintronics.
Discovery of a New Technique
The team encountered multiple obstacles while making this discovery. They first had to figure out how to create a clean interface between bilayers, which led to the breakthrough of employing ice as a transfer medium—a first in the field. By using a layer of thin ice to synthesize and transfer 2D materials, the team achieved interfaces that were clean and manageable. This innovative ice-assisted transfer method is more effective, quicker, and cost-efficient compared to other techniques.
Next, they needed to address the complexity of analyzing the material. They ultimately made their breakthrough using four-dimensional transmission electron microscopy (4D-TEM) in collaboration with other researchers. They successfully created the twisted bilayer 2D structure, subsequently revealing the new vortex electric field.
Looking to the Future
With a broad range of potential applications for the various twist angles, the team is excited to continue developing their research based on this discovery and to explore its complete range of possibilities.
The next phase of their research will investigate further manipulation of the material, such as whether stacking additional layers is feasible or if similar effects can be achieved with different materials. Having secured a patent for their ice-assisted transfer technique, the team is eager to see if this method could facilitate further discoveries globally, given that it allows for clean bilayer interfaces without the need for elaborate and expensive processes.
“This study could spark a new area of research focused on twisting vortex fields in nanotechnology and quantum technology,” concluded Professor Ly, who underscored that although this discovery is still in its early application stages, it has the potential to be a game-changer in various fields, including memory, quantum computing, spintronics, and sensing devices.
The article titled “Polar and quasicrystal vortex observed in twisted-bilayer molybdenum disulfide” was recently published in Science.
The paper’s corresponding authors include Professor Ly, Professor Zhao Jiong, and Professor Yang Ming from the Department of Applied Physics at Hong Kong Polytechnic University. Additional collaborators are Professor Lee Chun-Sing from the Department of Chemistry at CityUHK, and Professor Lau Shu Ping from the Department of Applied Physics at Hong Kong Polytechnic University.
