Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nano-sandwich Triggers Novel Electron Behavior

06.05.2009
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.

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 UC 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.

Liese Greensfelder | EurekAlert!
Further information:
http://www.ucdavis.edu

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>