Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electron correlations in carbon nanostructures

03.12.2019

Physicists from Kiel and Copenhagen elucidate the behaviour of electrons in graphene nanoribbons

New materials are needed to further reduce the size of electronic components and thus make devices such as laptops and smartphones faster and more efficient. Tiny nanostructures of the novel material graphene are promising in this respect.


The graphene nanoribbon (center) consists of a single layer of honeycomb carbon atoms. The ribbon is only a few carbon atoms wide and has different electrical properties depending on its shape and width. The local density of the electrons is increased at the edges, as the dark red areas in the boxes show.

Copyright: Jan-Philip Joost, AG Bonitz

Graphene consists of a single layer of carbon atoms and, among other things, has a very high electrical conductivity. However, the extreme spatial confinement in such nanostructures influences strongly their electronic properties.

A team led by Professor Michael Bonitz of the Institute for Theoretical Physics and Astrophysics (ITAP) at Kiel University has now succeeded in simulating the detailed behavior of electrons in these special nanostructures using an elaborate computational model. This knowledge is crucial for the potential use of graphene nanostructures in electronic devices.

Precise simulation of the properties of electrons in nanostructures
Last year, two research teams succeeded independently of each other in fabricating narrow, atomically precise graphene nanoribbons and measuring their electron energies.

The width of the nanoribbons varies in a precisely controlled manner. Each section of the nanoribbons has its own energy states with their own electronic structure. "However, the measurement results could not be completely reproduced by previous theoretical models," says Bonitz, who heads the Chair of Statistical Physics at ITAP.

Together with his PhD student Jan-Philip Joost and their Danish colleague Professor Antti-Pekka Jauho from the Technical University of Denmark (DTU), they developed an improved model which led to an excellent agreement with the experiments. The physicists present their theoretical results in the current issue of the renowned journal Nano Letters.

The basis for the new and more precise computer simulations was the assumption that the deviations between the experiment and previous models were caused by the details of the mutual repulsion of the electrons.

Although this Coulomb interaction also exists in metals, and indeed was included in earlier simulations in a rough way, the effect is much greater in the small graphene nanoribbons, and requires a detailed analysis.

The electrons are expelled from their original energy states and have to 'search' for other places, as Bonitz explains: "We were able to prove that correlation effects due to the Coulomb interaction of the electrons have a dramatic influence on the local energy spectrum".

The shape of nanoribbons determines their electronic properties
How the permissible energy values of the electrons depend on the length, width and shape of the nanostructures has been clarified by the team by investigating many such nanoribbons.

"The energy spectrum also changes when the geometry of the nanoribbons, their width and shape, is modified," adds Joost. "For the first time, our new data allow precise predictions to be made as to how the energy spectrum can be controlled by specifically varying the shape of the nanoribbons," says Jauho from the DTU in Copenhagen.

The researchers hope that these predictions will now also be tested experimentally and lead to the development of new nanostructures. Such systems can make important contributions to the further miniaturisation of electronics.

Image for download:
https://www.uni-kiel.de/de/pressemitteilungen/2019/375-Graphen.jpg
Caption: The graphene nanoribbon (center) consists of a single layer of honeycomb carbon atoms. The ribbon is only a few carbon atoms wide and has different electrical properties depending on its shape and width. The local density of the electrons is increased at the edges, as the dark red areas in the boxes show.
Copyright: Jan-Philip Joost, AG Bonitz

Scientific contact:
Prof. Dr. Michael Bonitz
Institut für Theoretische Physik und Astrophysik
Tel.: 0431-880-4122
bonitz@theo-physik.uni-kiel.de
Web: www.theo-physik.uni-kiel.de/~bonitz

Details, which are only a millionth of a millimetre in size: this is what the priority research area "Kiel Nano, Surface and Interface Science – KiNSIS" at Kiel University has been working on. In the nano-cosmos, different laws prevail than in the macroscopic world - those of quantum physics. Through intensive, interdisciplinary cooperation between physics, chemistry, engineering and life sciences, the priority research area aims to understand the systems in this dimension and to implement the findings in an application-oriented manner. Molecular machines, innovative sensors, bionic materials, quantum computers, advanced therapies and much more could be the result.

More information at www.kinsis.uni-kiel.de

Wissenschaftliche Ansprechpartner:

Prof. Dr. Michael Bonitz
Institut für Theoretische Physik und Astrophysik
Tel.: 0431-880-4122
bonitz@theo-physik.uni-kiel.de
Web: www.theo-physik.uni-kiel.de/~bonitz

Originalpublikation:

Jan-Philip Joost, Antti-Pekka Jauho, Michael Bonitz, Correlated Topological States in Graphene Nanoribbon Heterostructures, Nano Letters (2019)
DOI:10.1021/acs.nanolett.9b04075, https://pubs.acs.org/articlesonrequest/AOR-cxJ6Abf9gQsphD6q3TCH

Weitere Informationen:

https://www.uni-kiel.de/en/details/news/375-graphen

Dr. Boris Pawlowski | Christian-Albrechts-Universität zu Kiel

More articles from Physics and Astronomy:

nachricht Supporting structures of wind turbines contribute to wind farm blockage effect
13.12.2019 | American Institute of Physics

nachricht Chinese team makes nanoscopy breakthrough
13.12.2019 | Chinese Academy of Sciences Headquarters

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Supporting structures of wind turbines contribute to wind farm blockage effect

13.12.2019 | Physics and Astronomy

Chinese team makes nanoscopy breakthrough

13.12.2019 | Physics and Astronomy

Tiny quantum sensors watch materials transform under pressure

13.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>