Tuning Graphene

 


New research was released in Physical Review Letters. It discusses a new method for tuning electronic bands in graphene. Their work highlights the use of artificial superlattice fields for changing the band dispersions of graphene.

There are many traditional band engineering methods, including interfacial strain, alloying and the use of heterostructures. These methods have limitations, in particular providing in situ and control over the engineered band structures. This changed with the invention of van der Waals (vdW) materials like graphene. It has opened new roads for structure engineering, making possible gating and even moire heterostructures. 

These possibilities allow for the modification of energy bands and can lead to various previously unknown physical phenomena. 

The biggest obstacle is the precise control of band structures to attain these specific electronic properties. In the past, these methods are not as flexible and do not have the ability to selectively change the dispersion of the bands.

  Researchers are actively working on the problem. They introduced a new method of band engineering. By using kagome, the scientists created a kagome superlattice  to manipulate the Dirac bands in graphene. 

The kagome superlattice was created with a large period of 80 nm. This size is important for compressing and folding the high-energy bands into a low energy system that can be observed and manipulated. 

A unique piece of information the researchers discovered is the use of a high-order potential within the kagome. This allows for the band structures to be organized in different ways, which can lead to dispersion-selection band modulation.

The kagome lattice used the van der Waals technique and electron beam lithography to create a gate for graphene. 

Researchers were able to control density and strength in the graphene. By adjusting the voltage applied to the doped silicon and the local gate, researchers were able to observe the change in distribution of weight among the Dirac peaks.

Another interesting thing observed is the application of a magnetic field. It was shown to weaken the superlattice’s impact on the band structure. This in turn reactivates the Dirac band, adding to the control of electronic properties of the material.

This new research offers unique unprecedented control over band structure engineering.

Professor Zeng Changgan from the University of Science and Technology of China (USTC) of the Chinese Academy of Science (CAS), Professor Sheng Junyuan from Wuhan University and Professor Francisco Guinea from IMDEA Nanociencia in Spain participated in this research. 

Comments

Post a Comment

Popular posts from this blog

Mike Giradi from Stereotimes commentary on Holostage Room Treatments

I have been  friends with Mike Giradi for a few years and he has helped me test numerous designs .    I was so honored a few weeks ago when he agreed to give these Holostages a few words.  From. Mike G. The sound was a little closed in at first, but then it really opened up to prove it is another great audio product. The noise floor is greatly reduced. I am hearing details I've never heard before. When it's in the recording, the soundstage widens in all directions. The timbre of each instrument is spot on. The six Holostages installed in my room aided in the C13 alignment of air molecules to a far greater extent than the Bybee IQSE devices I had previously been using. Every instrument had greater depth, pop and presence. Listening to classical music on movie soundtracks is incredible now. The Holostages installed on my BACCH4MAC and monoblocks was the answer to what was needed. The noise floor dropped significantly in both cases resulting in greater clarity and music...
Read more

Queen Bee 🐝

Image
  Bees hide an interesting secret. When the hive loses its queen, who alone is able to give life to the colony and maintain order in a perfectly organized society, all seems lost. The life of the hive slows down. Without new eggs, the future is lost. In a few weeks, the colony may be doomed. But the bees do not panic. Nor do they expect salvation from outside. Demonstrating extraordinary collective intelligence and profound instincts, they trigger spectacular emergency procedures, almost unimaginable in a world dominated by insects. --- ◆ The transformation begins with a simple but essential choice The worker bees choose common larvae - those who would normally be mere workers. They are nothing special. They are not born different. But their fate changes completely. They are chosen to receive a special food: royal jelly. A rare substance, produced by healthy bees, rich in proteins, vitamins and bioactive compounds. This is royal food in the purest sense of the word. The larvae fed ...
Read more

Novel Acoustic Wave Discovered

Image
  A new diffraction phenomenon was researched and published on January 14, 2025. The team was led by Tohoku University with collaboration from the Japan atomic energy agency and the RIKEN Center for emergent matter science. Surface acoustic waves (SAWs) are elastic vibrations. They travel along the surface of materials, not unlike ripples on a pond. SAWs are an important part of frequency filters used in every day devices like our cell phones. These devices change electrical signals in vibrations, or ripples. This occurs because of the piezoelectric  effect and it enables efficient signal processing. During this experiment, the team created a periodic array of magnetic nanoscale materials. The magnetic array is a sort of specialized grating that the waves passed through. The scientists were surprised. Instead of the usual symmetric defraction, the team saw something different. They observed a completely new, asymmetrical diffraction of SAWs called ‘non-reciprocal defraction’....
Read more