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 Electrocatalysis can advance green transition
23.01.2017 | Technical University of Denmark

nachricht Quantum optical sensor for the first time tested in space – with a laser system from Berlin
23.01.2017 | Ferdinand-Braun-Institut Leibniz-Institut für Höchstfrequenztechnik

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: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Tracking movement of immune cells identifies key first steps in inflammatory arthritis

23.01.2017 | Health and Medicine

Electrocatalysis can advance green transition

23.01.2017 | Physics and Astronomy

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>