Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Nano-sandwich triggers novel electron behavior

Abstract:
A material just six atoms thick in which electrons appear to be guided by conflicting laws of physics depending on their direction of travel has been discovered by a team of physicists at the University of California, Davis. Working with computational models, the team has found that the electrons in a thin layer of vanadium dioxide sandwiched between insulating sheets of titanium dioxide exhibit one set of properties when moving in forward-backward directions, and another set when moving left to right.

Nano-sandwich triggers novel electron behavior

Davis, CA | Posted on May 4th, 2009

With its unique properties, the material could open up a new world of possibilities in the emerging field of spintronics technology, which takes advantage of the magnetic as well as the electric properties of electrons in the design of novel electronic devices.

A paper describing the material and its properties appears in the April 22 issue of Physical Review Letters.

"Our model is demonstrating a new kind of band structure [dynamics of electrons], which no one has been aware of before," said Warren Pickett, professor and chair of the physics department at UC Davis. "We think that some of the transport properties we're seeing in the material — electrical conduction and conduction in a magnetic field — will be different than anything seen before."

The discovery comes five years after a group at the University of Manchester in England first isolated graphene, a single-layer lattice of carbon atoms. That material, too, had unique electronic properties, and it sparked a huge surge of interest among physicists and materials scientists, who have published hundreds of papers on it. The team termed the behavior of electrons in graphene "Dirac-like" because of its similarity to the behavior of massless particles as described in an equation formulated by the illustrious theoretical physicist Paul Dirac.

Now Pickett and co-author Victor Pardo, a professor at the University of Santiago de Compostela in Spain who was a visiting professor at UC Davis when he did the work, have coined the term "semi-Dirac" to characterize the behavior of electrons in their multilayered vanadium dioxide lattice.

In this nanomaterial, Pickett explained, the sandwiching layers of the insulating titanium dioxide confine the vanadium, enforcing two-dimensional motion on its electrons. When the electrons move in one direction, they behave in the usual fashion, as particles with mass, but movement in the other direction produces behavior characteristic of particles without mass.

"It's important that we use precisely three layers of vanadium dioxide," Pickett said. "Using one or two layers only produces a magnetic insulator, while anything more than three layers produces a fairly normal magnetic metal that exhibits conducting behavior. The semi-Dirac system is neither conducting nor insulating."

A big advantage that the vanadium lattice has over the one-layer thick graphene is greater rigidity, which will make it easier to etch into experimental or functional shapes, Pickett said.

For the time being, the material exists only as a computational model. Yet many of the basic, underlying processes and principles of physics are first established theoretically, with or without computational analysis, Pickett said.

Pickett and Pardo have teamed with UC Davis physics professor Rajiv Singh and graduate student Swapnonil Banerjee to investigate the material's properties. The team has constructed a classical mathematical model called a "tight-binding" model that they expect will promote a theoretical understanding of the material at the most basic level. "We're pretty confident that this nanostructure can be made, and made clean enough to demonstrate the properties the model has demonstrated," Pickett said.

The group has already achieved a basic understanding of the low energy behavior of semi-Dirac systems and has submitted a second paper for publication describing the peculiar behavior.

####

About University of California, Davis
For 100 years, UC Davis has engaged in teaching, research and public service that matter to California and transform the world. Located close to the state capital, UC Davis has 31,000 students, an annual research budget that exceeds $500 million, a comprehensive health system and 13 specialized research centers. The university offers interdisciplinary graduate study and more than 100 undergraduate majors in four colleges — Agricultural and Environmental Sciences, Biological Sciences, Engineering, and Letters and Science — and advanced degrees from six professional schools — Education, Law, Management, Medicine, Veterinary Medicine and the Betty Irene Moore School of Nursing.

For more information, please click here

Contacts:
Warren Pickett
Physics
(530) 752-5989


Liese Greensfelder
UC Davis News Service
(530) 752-6101

Copyright © University of California, Davis

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

INRS and ELI deepen strategic partnership to train the next generation in laser science:PhD students will benefit from international mobility and privileged access to cutting-edge infrastructure June 6th, 2025

Electrifying results shed light on graphene foam as a potential material for lab grown cartilage June 6th, 2025

Quantum computers simulate fundamental physics: shedding light on the building blocks of nature June 6th, 2025

A 1960s idea inspires NBI researchers to study hitherto inaccessible quantum states June 6th, 2025

Spintronics

An earth-abundant mineral for sustainable spintronics: Iron-rich hematite, commonly found in rocks and soil, turns out to have magnetic properties that make it a promising material for ultrafast next-generation computing April 25th, 2025

‘Brand new physics’ for next generation spintronics: Physicists discover a unique quantum behavior that offers a new way to manipulate electron-spin and magnetization to push forward cutting-edge spintronic technologies, like computing that mimics the human brain January 17th, 2025

Researchers discover a potential application of unwanted electronic noise in semiconductors: Random telegraph noises in vanadium-doped tungsten diselenide can be tuned with voltage polarity August 11th, 2023

Quantum materials: Electron spin measured for the first time June 9th, 2023

Chip Technology

A 1960s idea inspires NBI researchers to study hitherto inaccessible quantum states June 6th, 2025

Programmable electron-induced color router array May 14th, 2025

Enhancing power factor of p- and n-type single-walled carbon nanotubes April 25th, 2025

Ultrafast plasmon-enhanced magnetic bit switching at the nanoscale April 25th, 2025

Announcements

INRS and ELI deepen strategic partnership to train the next generation in laser science:PhD students will benefit from international mobility and privileged access to cutting-edge infrastructure June 6th, 2025

Electrifying results shed light on graphene foam as a potential material for lab grown cartilage June 6th, 2025

Quantum computers simulate fundamental physics: shedding light on the building blocks of nature June 6th, 2025

A 1960s idea inspires NBI researchers to study hitherto inaccessible quantum states June 6th, 2025

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