Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > A graphene superconductor that plays more than one tune: Researchers at Berkeley Lab have developed a tiny toolkit for scientists to study exotic quantum physics

The graphene/boron nitride moiré superlattice material is composed of three atomically thin (2D) layers of graphene (gray) sandwiched between 2D layers of boron nitride (red and blue) to form a repeating pattern called a moiré superlattice. Superconductivity is indicated by the light-green circles.

CREDIT
Guorui Chen et al./Berkeley Lab
The graphene/boron nitride moiré superlattice material is composed of three atomically thin (2D) layers of graphene (gray) sandwiched between 2D layers of boron nitride (red and blue) to form a repeating pattern called a moiré superlattice. Superconductivity is indicated by the light-green circles. CREDIT Guorui Chen et al./Berkeley Lab

Abstract:
Researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a graphene device that's thinner than a human hair but has a depth of special traits. It easily switches from a superconducting material that conducts electricity without losing any energy, to an insulator that resists the flow of electric current, and back again to a superconductor - all with a simple flip of a switch. Their findings were reported today in the journal Nature.

A graphene superconductor that plays more than one tune: Researchers at Berkeley Lab have developed a tiny toolkit for scientists to study exotic quantum physics

Berkeley, CA | Posted on July 19th, 2019

"Usually, when someone wants to study how electrons interact with each other in a superconducting quantum phase versus an insulating phase, they would need to look at different materials. With our system, you can study both the superconductivity phase and the insulating phase in one place," said Guorui Chen, the study's lead author and a postdoctoral researcher in the lab of Feng Wang, who led the study. Wang, a faculty scientist in Berkeley Lab's Materials Sciences Division, is also a UC Berkeley physics professor.

The graphene device is composed of three atomically thin (2D) layers of graphene. When sandwiched between 2D layers of boron nitride, it forms a repeating pattern called a moiré superlattice. The material could help other scientists understand the complicated mechanics behind a phenomenon known as high-temperature superconductivity, where a material can conduct electricity without resistance at temperatures higher than expected, though still hundreds of degrees below freezing.

In a previous study, the researchers reported observing the properties of a Mott insulator in a device made of trilayer graphene. A Mott insulator is a class of material that somehow stops conducting electricity at hundreds of degrees below freezing despite classical theory predicting electrical conductivity. But it has long been believed that a Mott insulator can become superconductive by adding more electrons or positive charges to make it superconductive, Chen explained.

For the past 10 years, researchers have been studying ways to combine different 2D materials, often starting with graphene - a material known for its ability to efficiently conduct heat and electricity. Out of this body of work, other researchers had discovered that moiré superlattices formed with graphene exhibit exotic physics such as superconductivity when the layers are aligned at just the right angle.

"So for this study we asked ourselves, 'If our trilayer graphene system is a Mott insulator, could it also be a superconductor?'" said Chen.

Opening the gate to a new world of physics

Working with David Goldhaber-Gordon of Stanford University and the Stanford Institute for Materials and Energy Sciences at SLAC National Accelerator Laboratory, and Yuanbo Zhang of Fudan University, the researchers used a dilution refrigerator, which can reach intensely cold temperatures of 40 millikelvins - or nearly minus 460 degrees Fahrenheit - to cool the graphene/boron nitride device down to a temperature at which the researchers expected superconductivity to appear near the Mott insulator phase, said Chen.

Once the device reached a temperature of 4 kelvins (minus 452 degrees Fahrenheit), the researchers applied a range of electrical voltages to the tiny top and bottom gates of the device. As they expected, when they applied a high vertical electrical field to both the top and bottom gates, an electron filled each cell of the graphene/boron nitride device. This caused the electrons to stabilize and stay in place, and this "localization" of electrons turned the device into a Mott insulator.

Then, they applied an even higher electrical voltage to the gates. To their delight, a second reading indicated that the electrons were no longer stable. Instead, they were shuttling about, moving from cell to cell, and conducting electricity without loss or resistance. In other words, the device had switched from the Mott insulator phase to the superconductor phase.

Chen explained that the boron nitride moiré superlattice somehow increases the electron-electron interactions that take place when an electrical voltage is applied to the device, an effect that switches on its superconducting phase. It's also reversible - when a lower electrical voltage is applied to the gates, the device switches back to an insulating state.

The multitasking device offers scientists a tiny, versatile playground for studying the exquisite interplay between atoms and electrons in exotic new superconducting materials with potential use in quantum computers - computers that store and manipulate information in qubits, which are typically subatomic particles such as electrons or photons - as well as new Mott insulator materials that could one day make tiny 2D Mott transistors for microelectronics a reality.

"This result was very exciting for us. We never imagined that the graphene/boron nitride device would do so well," Chen said. "You can study almost everything with it, from single particles to superconductivity. It's the best system I know of for studying new kinds of physics," Chen said.

This study was supported by the Center for Novel Pathways to Quantum Coherence in Materials (NPQC), an Energy Frontier Research Center led by Berkeley Lab and funded by the DOE Office of Science. NPQC brings together researchers at Berkeley Lab, Argonne National Laboratory, Columbia University, and UC Santa Barbara to study how quantum coherence underlies unexpected phenomena in new materials such as trilayer graphene, with an eye toward future uses in quantum information science and technology.

###

Also contributing to the study were researchers from Shanghai Jiao Tong University and Nanjing University, China; the National Institute for Materials Science, Japan; and the University of Seoul, Korea.

####

About Lawrence Berkeley National Laboratory
Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 13 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab's facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy's Office of Science.

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

For more information, please click here

Contacts:
Theresa Duque

510-495-2418

Copyright © Lawrence Berkeley National Laboratory

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 Links

RELATED JOURNAL ARTICLE:

Related News Press

News and information

Cyborg heart could help scientists better understand the human organ August 21st, 2019

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

A first for cancer research’: New approach to study tumors August 20th, 2019

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Laboratories

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

2 Dimensional Materials

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

A modified device fabrication process achieves enhanced spin transport in graphene August 6th, 2019

Physicists make graphene discovery that could help develop superconductors: Rutgers-led research could reduce energy use, improve electronic devices August 1st, 2019

Graphene/ Graphite

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Physicists make graphene discovery that could help develop superconductors: Rutgers-led research could reduce energy use, improve electronic devices August 1st, 2019

Oddball edge wins nanotube faceoff: Rice U. theory shows peculiar 'Janus' interface a common mechanism in carbon nanotube growth July 29th, 2019

Superconductivity

Physicists make graphene discovery that could help develop superconductors: Rutgers-led research could reduce energy use, improve electronic devices August 1st, 2019

Researchers report new understanding of thermoelectric materials: Discovery leads to promising new materials for converting waste heat to power June 21st, 2019

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

UCI scientists create new class of two-dimensional materials: Fabrication could help unlock new quantum computing and energy technologies June 6th, 2019

Quantum Physics

Research Reveals Exotic Quantum States in Double-Layer Graphene: Findings shed new light on the nature of electron interactions in quantum systems and establish a potential new platform for future quantum computers June 26th, 2019

Govt.-Legislation/Regulation/Funding/Policy

Cyborg heart could help scientists better understand the human organ August 21st, 2019

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Quantum Computing

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

RIT awarded NSF funding to conceptualize Quantum Photonic Institute: RIT will develop plan for open-access Quantum Foundry for quantum photonic circuits August 7th, 2019

Virginia Tech researchers lead breakthrough in quantum computing July 26th, 2019

Discoveries

Cyborg heart could help scientists better understand the human organ August 21st, 2019

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

A first for cancer research’: New approach to study tumors August 20th, 2019

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

Announcements

Cyborg heart could help scientists better understand the human organ August 21st, 2019

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

A first for cancer research’: New approach to study tumors August 20th, 2019

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

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

Cyborg heart could help scientists better understand the human organ August 21st, 2019

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

A first for cancer research’: New approach to study tumors August 20th, 2019

Stanford builds a heat shield just 10 atoms thick to protect electronic devices: Atomically thin heat shields could be up to 50,000 times thinner than current insulating materials in cell phones and laptops August 19th, 2019

Research partnerships

Research brief: A novel cellular process to engulf nano-sized materials August 20th, 2019

A first for cancer research’: New approach to study tumors August 20th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Quantum nanoscience

Dresden physicists use nanostructures to free photons for highly efficient white OLEDs: Trapped light particles July 12th, 2019

Research Reveals Exotic Quantum States in Double-Layer Graphene: Findings shed new light on the nature of electron interactions in quantum systems and establish a potential new platform for future quantum computers June 26th, 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

2D crystals conforming to 3D curves create strain for engineering quantum devices June 7th, 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