Tungsten deuteride - a new two-dimensional material promises to be a candidate for spintronics

The compound semiconductor website reported that research teams at the US Department of Energy's Berkeley Lab and the University of California, Berkeley, have produced a thin atomic material, making it a promising candidate for "spintronics." .

This material, called 1T "phase tungsten (1T"-WTe2), bridges two research areas: 2D materials, including single-layer materials that exhibit different properties from their thicker counterparts, such as graphene; topological materials, where Electrons can move rapidly without resistance in a predictable manner, and are not affected by defects that normally hinder their movement.

At the edge of this material, the rotation of electrons and their momentum are closely related and predictable.

This material is called a topological insulator because its inner surface is not conductive and its conductivity (flow of electrons) is confined to its edges.

The latest experimental evidence can promote the use of this material to test objects for next-generation applications, such as new electronic devices that manipulate spin properties and can carry and store data more efficiently than current devices.

Sung-Kwan Mo, a physicist and staff scientist at Berkeley Laboratory Advanced Light Sources (ALS), said: "This material should be very useful for spintronics research. The flow of electrons is completely related to the direction of their spin, and is limited to The edge of the material. The electrons will travel in one direction and there is a type of rotation, which is useful for spintronic devices." It is conceivable that devices made of this material carry data more fluidly than current typical electronic devices. , with less power demand and heat accumulation.

“We are excited that we have discovered another series of materials (2-D topological insulators) that can explore the physical characteristics of 2-D topological insulators and carry out experiments that may lead to future applications.” Stanford University Scientist, SLAC Shen Zhixun, a professor of physics at the National Accelerator Laboratory’s scientific and technical consultancy and the co-leader of the study, said. He added: "This general class of material has been shown to be stable and well maintained under a variety of experimental conditions, which should make the field faster."

The material was manufactured and studied under ALS (an X-ray research facility). Dr. Tang Shujie, a postdoctoral fellow and a co-principal author of the study from Berkeley Laboratories and Stanford University, used a 3-nanometer-thick crystallographic sample of a molecular beam epitaxial growth process in an ALS high-purity, vacuum-sealed compartment.

Research began in 2015 and involved more than 20 researchers in two disciplines. The research team also benefited from calculations at the Berkeley National Energy Research Center for Scientific Computing (NERSC).

2D materials have unique electronic properties and are considered key to their application in spintronics applications. By selectively stacking different types of materials, global R&D work on customized materials for specific applications is very active.

"The researchers tried to sandwich different materials on top of each other to adjust the materials like Lego blocks according to their wishes. Now that we have experimental proof of the nature of this material, we want to stack with other materials to see how these properties change ” said Mo.

A typical problem with creating such a designer material from a thin layer of atoms is that the material often has nanoscale defects that are difficult to eliminate and may affect its performance. However, since 1T"-WTe2 is a topological insulator, its electronic properties are elastic.

“At the nanoscale, it may not be a perfect crystal,” Mo said. “But the beauty of the topological material is that even if your crystals are not perfect, the edge state will still exist, and the disadvantages will not destroy the key performance.”

Looking ahead, researchers aim to develop larger sample materials and discover how to selectively adjust and emphasize specific properties. In addition to its topological features, the "sisters" of similar properties studied by its research team are also considered to be light-sensitive and useful for solar cells and optoelectronics, which control light used in electronic devices.