MagLab scientists working with graphene — a stronger-than steel, but feathery light material with a myriad of intriguing attributes — have observed new properties that bring this high-tech super material closer to everyday use.
Researchers from Columbia University working at the MagLab have observed a physical phenomenon in bilayer graphene that could usher in a new generation of quantum computers.
Using the high magnetic fields available at the NHMFL, users from MIT were able to observe a quantum spin hall (QSH) state in graphene. The QSH state results in two oppositely oriented spin currents flowing clockwise and counter clockwise around the edge of the graphene flake without dissipation effects. This discovery further advances the exciting work being done to bring about spin based electronics.
Utilizing the sensitivity of the NHMFL optics facility, a team of scientists from Georgia Tech, Sandia National Laboratories, Institut Néel, Université Paris-Sud and the NHMFL were able to observe collective oscillations of Dirac Fermions in graphene nanoribbons. The observed effect is tunable by varying the width of the graphene nanoribbons and the applied magnetic field. This observation raises the possibility of graphene based tunable THz devices.
MagLab physicist Oskar Vafek’s latest groundbreaking work on superconductivity.
Using the 45T hybrid magnet, researchers uncover the quantum Hall effect in hydrogenated graphene.
Thanks to conditions created by the MagLab’s 45 tesla hybrid magnet, scientists have made a technological breakthrough on graphene: When they placed it on top of hexagonal boron nitride, graphene became a semiconductor.
Tilted magnetic fields were used to classify the broken symmetry states by their spin polarization. It was found that graphene turns into either a spin ferromagnet or some variety of density wave.
A layer of graphite one atom thick holds great promise for the future of microelectronics. It's called graphene, and University of Manchester physicists Andre Geim and Kostya Novoselov this week won a 2010 Nobel Prize for creating it.
"It's thrilling when scientists affiliated in some way with the Mag Lab receive such a well-deserved honor," said Greg Boebinger, director of the National High Magnetic Field Laboratory. Boebinger co-authored a landmark 2007 Science paper, "Room-Temperature Quantum Hall Effect in Graphene," with the Nobel laureates.
"What started as a small but exciting development has evolved into a major research effort," said Boebinger, noting that 17 different user groups studied graphene at the Magnet Lab in 2009, and that interest in the material shows no signs of abating.
Geim and Novoselov famously created graphene using a simple "Scotch tape" technique — humble beginnings for a material that could transform computers, cell phones, and other technologies. They placed a piece of tape on some graphite and pulled it off. When they examined the material trace with a microscope, they were able to find flecks that were only one layer of atoms thick.
Graphene is a hexagonal array of carbon atoms so thin it's virtually see-through. It has remarkable electronic and mechanical properties, and is as good a conductor of electricity as copper and is stronger than steel. Because of its amazing properties, some scientists speculate that graphene could one day replace silicon as the principal component in semiconductor devices, leading to smaller, faster and more versatile electronic devices.
But as with so many things in science, there's still a lot to learn about graphene before the engineers start using it for practical purposes. The race for answers has placed the material at the intellectual frontier of condensed matter physics, which means increased demand for magnet time at the Mag Lab. Of the 17 user groups researching graphene in 2009, six of the groups consisted of new users, and between the lab's DC Field and Pulsed Magnet user programs, that number is expected to grow larger still.
"Graphene is a fascinating material for about 20 different reasons, but to a lot of physicists, the most interesting thing about it is what happens to it when it's put in a magnetic field," said Paul Cadden-Zimansky, a postdoctoral associate who splits his time between the Magnet Lab and Columbia University. "The higher the field, the more interesting it gets."
Driving that point home, Pulsed Field Facility user Layla Booshehri from Professor Jun Kono research group Rice University recently collaborated with Pulsed Field Facility Director Chuck Mielke to probe single-layer graphene at fields up to 170 tesla using the lab's single-turn magnet. The magneto absorption measurements reveal a wavelength-dependent resonance at high magnetic fields, allowing the researchers to pinpoint the Fermi energy of the doped graphene.
The National High Magnetic Field Laboratory develops and operates state-of-the-art, high-magnetic-field facilities that faculty and visiting scientists and engineers use for research. The laboratory is sponsored by the National Science Foundation and the state of Florida. To learn more visit www.magnet.fsu.edu.