Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Hall effect becomes viscous in graphene: Researchers at the University of Manchester in the UK have discovered that electrons in graphene act like a very unique liquid

Abstract:
Researchers at The University of Manchester in the UK have discovered that the Hall effect - a phenomenon well known for more than a century - is no longer as universal as it was thought to be.

Hall effect becomes viscous in graphene: Researchers at the University of Manchester in the UK have discovered that electrons in graphene act like a very unique liquid

Manchester, UK | Posted on February 28th, 2019

In the research paper published in Science this week, the group led by Prof Sir Andre Geim and Dr Denis Bandurin found that the Hall effect can even be signifcantly, if electrons strongly interact with each other giving rise to a viscous flow. The new phenomenon is important at room temperature - something that can have important implications for when making electronic or optoelectronic devices.

Just like molecules in gases and liquids, electrons in solids frequently collide with each other and can thus behave like viscous fluids too. Such electron fluids are ideal to find new behaviours of materials in which electron-electron interactions are particularly strong. The problem is that most materials are rarely pure enough to allow electrons to enter the viscous regime. This is because they contain many impurities off which electrons can scatter before they have time to interact with each other and organise a viscous flow.

Graphene can come in very useful here: the carbon sheet is a highly clean material that contains only a few defects, impurities and phonons (vibrations of the crystal lattice induced by temperature) so that electron-electron interactions become the main source of scattering, which leads to a viscous electron flow.

"In previous work, our group found that electron flow in graphene can have a viscosity as high as ?0.1 m2s-1, which is 100 times higher than that of honey," said Dr Bandurin "In this first demonstration of electron hydrodynamics, we discovered very unusual phenomena like negative resistance, electron whirlpools and superballistic flow."

Even more unusual effects occur when a magnetic field is applied to graphene's electrons when they are in the viscous regime. Theorists have already extensively studied electro-magnetohydrodynamics because of its relevance for plasmas in nuclear reactors and in neutron stars, as well as for fluid mechanics in general. But, no practical experimental system in which to test those predictions (such as large negative magnetoresistance and anomalous Hall resistivity) was readily available until now.

In their latest experiments, the Manchester researchers made graphene devices with many voltage probes placed at different distances from the electrical current path. Some of them were less than one micron from each other. Geim and colleagues showed that while the Hall effect is completely normal if measured at large distances from the current path, its magnitude rapidly diminishes if probed locally, using contacts close to the current injector.

"The behaviour is radically different from the standard textbook physics" says Alexey Berdyugin, a PhD student who conducted the experimental work. "We observe that if the voltage contacts are far from the current contacts, we measure the old, boring Hall effect, instead of this new 'viscous Hall effect'. But, if we place the voltage probes near the current injection points - the area in which viscosity shows up most dramatically as whirlpools in electron flow - then we find that the Hall effect diminishes.

"Qualitative changes in the electron flow caused by viscosity persist even at room temperature if graphene devices are smaller than one micron in size, says Berdyugin. "Since this size has become routine these days as far as electronic devices are concerned, the viscous effects are important when making or studying graphene devices."

####

For more information, please click here

Contacts:
Ben Robinson

01-612-750-134

Copyright © University of Manchester

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

University of Konstanz researchers create uniform-shape polymer nanocrystals: Researchers from the University of Konstanz's CRC 1214 'Anisotropic Particles as Building Blocks: Tailoring Shape, Interactions and Structures' generate uniform-shape nanocrystals using direct polymeriz June 14th, 2019

Small currents for big gains in spintronics: A new low-power magnetic switching component could aid spintronic devices June 14th, 2019

University of Aberdeen use the Deben CT5000 to observe compressive damage mechanisms in syntactic foam June 14th, 2019

Magnetism

Small currents for big gains in spintronics: A new low-power magnetic switching component could aid spintronic devices June 14th, 2019

New interaction between thin film magnets discovered: Physicists of Johannes Gutenberg University Mainz lay the foundations for new three-dimensional spin structures June 7th, 2019

Graphene/ Graphite

Making graphene-based desalination membranes less prone to defects, better at separating June 13th, 2019

Flexible generators turn movement into energy: Rice University's laser-induced graphene nanogenerators could power future wearables June 2nd, 2019

Laser technique could unlock use of tough material for next-generation electronics: Researchers make graphene tunable, opening up its band gap to a record 2.1 electronvolts May 30th, 2019

Possible Futures

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

Perfect diamagnetism observation of high-temperature superconductivity in compressed H2S June 14th, 2019

Mysterious Majorana quasiparticle is now closer to being controlled for quantum computing: Princeton researchers detect a robust Majorana quasiparticle and show how it can be turned on and off June 14th, 2019

Chip Technology

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

Mysterious Majorana quasiparticle is now closer to being controlled for quantum computing: Princeton researchers detect a robust Majorana quasiparticle and show how it can be turned on and off June 14th, 2019

Small currents for big gains in spintronics: A new low-power magnetic switching component could aid spintronic devices June 14th, 2019

Optical computing/Photonic computing

New record: 3D-printed optical-electronic integration June 18th, 2019

New Video Highlights Specific Topics Sought in Call for Papers for the 2019 IEEE International Electron Devices Meeting (IEDM) June 13th, 2019

Quantum information gets a boost from thin-film breakthrough: Method opens new path to all-optical quantum computers, other technologies May 31st, 2019

2D borophene gets a closer look: Rice, Northwestern find new ways to image, characterize unique material April 11th, 2019

Discoveries

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

Mysterious Majorana quasiparticle is now closer to being controlled for quantum computing: Princeton researchers detect a robust Majorana quasiparticle and show how it can be turned on and off June 14th, 2019

University of Konstanz researchers create uniform-shape polymer nanocrystals: Researchers from the University of Konstanz's CRC 1214 'Anisotropic Particles as Building Blocks: Tailoring Shape, Interactions and Structures' generate uniform-shape nanocrystals using direct polymeriz June 14th, 2019

Announcements

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

University of Konstanz researchers create uniform-shape polymer nanocrystals: Researchers from the University of Konstanz's CRC 1214 'Anisotropic Particles as Building Blocks: Tailoring Shape, Interactions and Structures' generate uniform-shape nanocrystals using direct polymeriz June 14th, 2019

Small currents for big gains in spintronics: A new low-power magnetic switching component could aid spintronic devices June 14th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

New record: 3D-printed optical-electronic integration June 18th, 2019

Can break junction techniques still offer quantitative information at single-molecule level June 18th, 2019

Perfect diamagnetism observation of high-temperature superconductivity in compressed H2S June 14th, 2019

University of Konstanz researchers create uniform-shape polymer nanocrystals: Researchers from the University of Konstanz's CRC 1214 'Anisotropic Particles as Building Blocks: Tailoring Shape, Interactions and Structures' generate uniform-shape nanocrystals using direct polymeriz June 14th, 2019

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project