Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists tame ’hip hop’ atoms

16.09.2004


Precision placement may help in building nanoscale devices

In an effort to put more science into the largely trial and error building of nanostructures, physicists at the Commerce Department’s National Institute of Standards and Technology (NIST) have demonstrated new methods for placing what are typically unruly individual atoms at precise locations on a crystal surface. Reported in the Sept. 9, 2004, online version of the journal Science, the advance enables scientists to observe and control, for the first time, the movement of a single atom back and forth between neighboring locations on a crystal and should make it easier to efficiently build nanoscale devices "from the bottom up," atom by atom.

The NIST team was surprised to find that the atoms emitted a characteristic electronic "noise" as they moved between two different types of bonding sites on the crystal surface. By converting this electronic signal into an audio signal, the researchers were able to "hear" the switching take place. The sound resembles a hip hop musician’s rhythmic "scratching" and can be used by researchers to know in real time that atoms have moved into desired positions.



Several research groups already are using specialized microscopes to build simple structures by moving atoms one at a time. The NIST advance makes it easier to reliably position atoms in very specific locations. "What we did to the atom is something like lubricating a ball bearing so that less force is required to move it," says Joseph Stroscio, co-author of the Science paper.

Such basic nanoscale construction tools will be essential for computer-controlled assembly of more complex atomic-scale structures and devices. These devices will operate using quantum physics principles that only occur at the atomic scale, or may be the ultimate miniaturization of a conventional device, such as an "atomic switch" where the motion of a single atom can turn electrical signals on and off.

The research involved using a custom-built, cryogenic scanning tunneling microscope (STM) to move a cobalt atom around on a bed of copper atoms that are closely packed in a lattice pattern. In a typical STM, a needle-like tip is scanned over an electrically conducting surface and changes in current between the tip and the surface are used to make three-dimensional images of the surface topography. The tip can be brought closer to the surface to push or pull the cobalt atom.

In the research described in Science, NIST scientists discovered that the cobalt atom responds to both the STM tip and the copper surface, and that the atom "hops" back and forth between nearby bonding sites instead of gliding smoothly. With slight increases in the current flowing through the tip to the atom, the researchers were able to make the cobalt atom heat up and vibrate and weaken the cobalt-copper bonds. This induced the cobalt atom to hop between the two types of lattice sites, with the rate of transfer controlled by the amount of current flowing.

The NIST researchers also found that they could use the STM tip to reshape the energy environment around the cobalt atom. This allows control over the amount of time the cobalt atom spends in one of the lattice sites. Using this technique the researchers found they can even trap the cobalt atom in a lattice site that the atom normally avoids. Sounds of the "protesting" atom give rise to the "hip hop" scratching sound described in Science. "The impact of the work is twofold," says Stroscio. "We learned about the basic physics involved in atom manipulation, which will help us build future atomic-scale nanostructures and devices. We also learned that we can control the switching of a single atom, which has potential for controlling electrical activity in those devices."

The experiments represent initial steps in exploring a new system of measurement, atom-based metrology, in which single atoms are used as nanoscale probes to collect information about their environment. In particular, the NIST-built instrument can be used to draw detailed maps of binding sites on a metal surface that cannot be made with standard STM measurements.

The new results are among the earliest to be published based on work performed at NIST’s nanoscale physics facility, where scientists are using a computer-controlled STM to autonomously manipulate and control individual atoms, with the intent to build useful devices and nanostructures.

Laura Ost | EurekAlert!
Further information:
http://physics.nist.gov/Divisions/Div841/Gp3/Facilities/nano_phy.html
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht New quantum phenomena in graphene superlattices
19.09.2017 | Graphene Flagship

nachricht Solar wind impacts on giant 'space hurricanes' may affect satellite safety
19.09.2017 | Embry-Riddle Aeronautical University

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: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

Im Focus: Artificial Enzymes for Hydrogen Conversion

Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.

Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

New quantum phenomena in graphene superlattices

19.09.2017 | Physics and Astronomy

A simple additive to improve film quality

19.09.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>