Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Novel mechanism of electron scattering in graphene-like 2D materials

17.09.2019

Suggesting an unconventional way to manipulate the properties of 2D materials in the presence of a Bose-Einstein condensate, and an alternative strategy to design high-temperature superconductors

Understanding how particles behave at the twilight zone between the macro and the quantum world gives us access to fascinating phenomena, interesting from both the fundamental and application-oriented physics perspectives.


Hybrid system formed by combining Bose-Einstein condensate (BEC) and 2D electron gas (2DEG) in novel 2D materials, such as MoS2. Electrons (black spheres) move in 2D electron gas (2DEG, upper layer), and interact with other particles present in the lower layers, where photo-excited electrons and holes (gray spheres, h.) form bound electron-hole pairs. The red wiggly lines represent Coulomb forces acting between particles with opposite charges.

Credit: IBS


Resistivity as a function of temperature for MoS2 (red) and GaAs (green) in BEC-2DEG hybrid systems. Colored solid and dashed curves represent the unconventional contributions with one and two bogolons, respectively. Black dash, dotted, and dashed curves show the impurity and phonon contributions.

Credit: IBS

For example, ultra-thin graphene-like materials are a fantastic playground to examine electrons' transport and interactions. Recently, researchers at the Center for Theoretical Physics of Complex Systems (PCS), within the Institute for Basic Science (IBS, South Korea), in collaboration with the Rzhanov Institute of Semiconductor Physics (Russia) have reported on a novel electron scattering phenomenon in 2D materials. The paper is published in Physical Review Letters.

The team considered a sample which consists of two subsystems: one made of particles with integer spin (bosons) and the other made of particles with half-integer spin (fermions).

For the bosonic component, they modelled a gas of excitons (electron-positron pairs). At low temperatures, quantum mechanics can force a large number of bosonic particles to form a Bose-Einstein condensate (BEC). This state of matter has been reported in different materials, in particular, gallium arsenide (GaAs), and it has been predicted in molybdenum disulphide (MoS2).

The fermionic subsystem is a 2D electron gas (2DEG), where electrons are limited to move in two dimensions. It exhibits intriguing magnetic and electric phenomena, including superconductivity, that is, the passage of current without resistivity.

These phenomena are related to electron scattering, which is mainly due to impurities and phonons. The latter are vibrations of the crystal lattice. Their name derives from the Greek 'phonos', meaning sound, since long-wavelength phonons give rise to sound, but they also play a role in the temperature-dependent electrical conductivity of metals.

Bosons and fermions are very different at the quantum level, so what happens when we combine BEC and 2DEG? Kristian Villegas, Meng Sun, Vadim Kovalev, and Ivan Savenko have modelled electron transport in such hybrid system.

Beyond the conventional phonons and impurities, the team described an unconventional electron scattering mechanism in BEC-2DEG hybrid systems: the interactions of an electron with one or two Bogoliubov quanta (or bogolons) - excitations of the BEC with small momenta. Although phonons and bogolons share some common features, the team found that they have important differences.

According to the models, in high-quality MoS2 at a certain range of temperatures, resistivity caused by pairs of bogolons proved to be dominating over resistivity caused by single bogolons, acoustic phonons, single-bogolons, and impurities.

The reason of such difference is the mechanism of interaction between electrons and bogolons, which is of electric nature, as opposed to electron-phonon interaction described by the deformations of the sample.

This research might be useful for the design of novel high-temperature superconductors. An apparent paradox links conductivity and superconductivity: bad conductors are usually good superconductors. In the case of electron-phonon interactions, some materials that show poor conductivity, because of strong scattering of electrons by phonons, can become good superconductors at very low temperatures.

For the same reason, noble metals, such as gold, are good conductors, but bad superconductors. If this holds true also for electron-bogolon interactions, then the researchers hypothesise that designing a bad conductor, with high resistivity caused by electron-2 bogolons interactions, might lead to "good" superconductors.

"This work not only opens perspectives in designing hybrid structures with controllable dissipation, it reports on fundamentally different temperature-dependence of scattering at low and high temperatures and sheds light on optically controlled condensate-mediated superconductivity," explains Ivan Savenko, the leader of the Light-Matter Interaction in Nanostructures (LUMIN) team at PCS.

Media Contact

Dahee Carol Kim
clitie620@ibs.re.kr
82-428-788-133

 @IBS_media

http://www.ibs.re.kr/en/ 

Dahee Carol Kim | EurekAlert!
Further information:
http://dx.doi.org/10.1103/PhysRevLett.123.095301

More articles from Materials Sciences:

nachricht House cleaning on the nanoscale
08.04.2020 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht X-rays reveal in situ crystal growth of lead-free perovskite solar panel materials
08.04.2020 | University of Groningen

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The human body as an electrical conductor, a new method of wireless power transfer

Published by Marc Tudela, Laura Becerra-Fajardo, Aracelys García-Moreno, Jesus Minguillon and Antoni Ivorra, in Access, the journal of the Institute of Electrical and Electronics Engineers

The project Electronic AXONs: wireless microstimulators based on electronic rectification of epidermically applied currents (eAXON, 2017-2022), funded by a...

Im Focus: Belle II yields the first results: In search of the Z′ boson

The Belle II experiment has been collecting data from physical measurements for about one year. After several years of rebuilding work, both the SuperKEKB electron–positron accelerator and the Belle II detector have been improved compared with their predecessors in order to achieve a 40-fold higher data rate.

Scientists at 12 institutes in Germany are involved in constructing and operating the detector, developing evaluation algorithms, and analyzing the data.

Im Focus: When ions rattle their cage

Electrolytes play a key role in many areas: They are crucial for the storage of energy in our body as well as in batteries. In order to release energy, ions - charged atoms - must move in a liquid such as water. Until now the precise mechanism by which they move through the atoms and molecules of the electrolyte has, however, remained largely unknown. Scientists at the Max Planck Institute for Polymer Research have now shown that the electrical resistance of an electrolyte, which is determined by the motion of ions, can be traced back to microscopic vibrations of these dissolved ions.

In chemistry, common table salt is also known as sodium chloride. If this salt is dissolved in water, sodium and chloride atoms dissolve as positively or...

Im Focus: Harnessing the rain for hydrovoltaics

Drops of water falling on or sliding over surfaces may leave behind traces of electrical charge, causing the drops to charge themselves. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz have now begun a detailed investigation into this phenomenon that accompanies us in every-day life. They developed a method to quantify the charge generation and additionally created a theoretical model to aid understanding. According to the scientists, the observed effect could be a source of generated power and an important building block for understanding frictional electricity.

Water drops sliding over non-conducting surfaces can be found everywhere in our lives: From the dripping of a coffee machine, to a rinse in the shower, to an...

Im Focus: A sensational discovery: Traces of rainforests in West Antarctica

90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous

An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

13th AKL – International Laser Technology Congress: May 4–6, 2022 in Aachen – Laser Technology Live already this year!

02.04.2020 | Event News

 
Latest News

Something is Lurking in the Heart of Quasar 3C 279

08.04.2020 | Physics and Astronomy

Looking for new antibiotics

08.04.2020 | Life Sciences

Artificial light in the Arctic

08.04.2020 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>