Nav: Home

The moiré patterns of three layers change the electronic properties of graphene

March 08, 2019

Combining an atomically thin graphene and a boron nitride layer at a slightly rotated angle changes their electrical properties. Physicists at the University of Basel have now shown for the first time the combination with a third layer can result in new material properties also in a three-layer sandwich of carbon and boron nitride. This significantly increases the number of potential synthetic materials, report the researchers in the scientific journal Nano Letters.

Last year, researchers in the US caused a big stir when they showed that rotating two stacked graphene layers by a "magical" angle of 1.1 degrees turns graphene superconducting - a striking example of how the combination of atomically thin materials can produce completely new electrical properties.

Precision alignment

Scientists from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel have now taken this concept one step further. They placed a layer of graphene between two boron nitride layers, which is often serves to protect the sensitive carbon structure. Doing so, they aligned the layers very precisely with the crystal lattice of the graphene.

The effect observed by the physicists in Professor Christian Schönenberger's team is commonly known as a moiré pattern: when two regular patterns are superimposed, a new pattern results with a larger periodic lattice.

New three-layer superlattice

Lujun Wang, a member of the SNI PhD School and researcher in Schönenberger's team, also observed effects of this kind of superlattice when he combined layers of boron nitride and graphene. The atoms are arranged hexagonally in all layers. If they are stacked on top of each other, larger regular patterns emerge, with a size depending on the angle between the layers.

It had already been shown that this works with a two-layer combination of graphene and boron nitride, but the effects due to a second boron nitride layer had not yet been found.

When the physicists from Basel experimented with three layers, two superlattices were formed between the graphene and the upper and the lower boron nitride layer, respectively. The superposition of all three layers created an even larger superstructure than possible with only one layer.

Scientists are very interested in these types of synthetic materials, since the different moiré patterns can be used to change or artificially produce new electronic material properties.

"To put it simply, the atomic patterns determine the behavior of electrons in a material, and we are combining different naturally occurring patterns to create new synthetic materials," explains Dr. Andreas Baumgartner, who supervised the project. "Now we have discovered effects in these tailor-made electronic devices that are consistent with a three-layer superstructure," he adds.
-end-


University of Basel

Related Graphene Articles:

New chemical method could revolutionize graphene
University of Illinois at Chicago scientists have discovered a new chemical method that enables graphene to be incorporated into a wide range of applications while maintaining its ultra-fast electronics.
Searching beyond graphene for new wonder materials
Graphene, the two-dimensional, ultra lightweight and super-strong carbon film, has been hailed as a wonder material since its discovery in 2004.
New method of characterizing graphene
Scientists have developed a new method of characterizing graphene's properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials.
Chemically tailored graphene
Graphene is considered as one of the most promising new materials.
Beyond graphene: Advances make reduced graphene oxide electronics feasible
Researchers have developed a technique for converting positively charged (p-type) reduced graphene oxide (rGO) into negatively charged (n-type) rGO, creating a layered material that can be used to develop rGO-based transistors for use in electronic devices.
The Graphene 2017 Conference connects Barcelona with the international graphene-based industry
This prestigious Conference to be held at the Barcelona International Convention Centre (March 28-31) aims to bring together academia and industry to integrate new graphene technologies into practical applications.
Graphene from soybeans
A breakthrough by CSIRO-led scientists has made the world's strongest material more commercially viable, thanks to the humble soybean.
First use of graphene to detect cancer cells
By interfacing brain cells onto graphene, researchers at the University of Illinois at Chicago have shown they can differentiate a single hyperactive cancerous cell from a normal cell, pointing the way to developing a simple, noninvasive tool for early cancer diagnosis.
Development of graphene microwave photodetector
DGIST developed cryogenic microwave photodetector which is able to detect 100,000 times smaller light energy compared to the existing photedetectors.
Adding hydrogen to graphene
IBS researchers report a fundamental study of how graphene is hydrogenated.

Related Graphene Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...