Clocking the movements of atoms

With their special microscopes, scientists and engineers involved in nanotechnologies have been able to 'see' atoms for a while. Now, U.S. physicists have found a way to clock the movements of atoms at the nanometer scale. This could lead to new materials for improved memory applications in microelectronics.

With their special microscopes, scientists and engineers involved in nanotechnologies have been able to 'see' atoms for a while. But they couldn't clock these atoms' response to events which typically occur in nanoseconds. Now, U.S. physicists have found a way to clock the movements of atoms at the nanometer scale. In their experiments, they were able to literally watch atoms switching positions in ferroelectric materials. Adding the dimension of time to the observation of the nanoworld could lead to easier developments of "materials for improved memory applications in microelectronics." Read more...

Here is the introduction of a news release of the University of Wisconsin-Madison about this research project.

As scientists and engineers build devices at smaller and smaller scales, grasping the dynamics of how materials behave when they are subjected to electrical signals, sound and other manipulations has proven to be beyond the reach of standard scientific techniques.
But now a team of University of Wisconsin-Madison researchers has found a way to time such effects at the nanometer scale, in essence clocking the movements of atoms as they are manipulated using electric fields.

One of the researchers, Alexei Grigoriev, noted that "now we have a tool to look inside a device and see how it works at the spatial scale of nanometers and the time scale of nanoseconds."

And if you think it was easy to develop this tool, take a look at Alexei Grigoriev in his lab (Credit: University of Wisconsin-Madison).

Alexei Grigoriev in his lab

This research work has been done at the Argonne National Laboratory's Advanced Photon Source, "a synchrotron light source capable of generating very tightly focused beams of X-rays." And the researchers delivered X-rays to a thin film of a ferroelectric material over an area of only hundreds of nanometers.

Ferroelectric materials respond to electric fields by expanding or contracting their crystal lattice structures. [...] "Physically, the atoms switch position," Grigoriev explains. "And as devices are pushed to smaller sizes, they must switch in extremely short times. It requires new tools to see those dynamics."

The sample area map [below] "visualizes the polarization switching development in time. This visualization contains important physical values including polarization switching domain nucleation rate and growth directions of the domains as well as the domain wall velocities. (Credit: University of Wisconsin-Madison)

Clocking atoms at the nanoscale

For more information, this research work has been published by the journal Physical Review Letters under the name "Nanosecond Domain Wall Dynamics in Ferroelectric Pb(Zr,Ti)O3 Thin Films" (Vol. 96, No. 18, Art. 187601, May 12, 2006). Here are two links to the abstract and to the full paper (PDF format, 4 pages, 543 KB).

And if you're interested in the subject, you should also take a look at a poster presented at the Advanced Photon Source Users' Meeting in May 2006 under the name "Dynamics of strain and polarization in ferroelectrics" (PowerPoint format, 1 page, 3.92 MB). The above map is a combination of two illustrations coming from the technical poster mentioned above and this poster.

Sources: University of Wisconsin-Madison news release, May 18, 2006; and various web sites

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