Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Probing polarization puzzles

28.03.2014

Using electron beams to encode data in nanocrystals could help to improve the capacity of computer memory devices

Ferroelectric materials have an intrinsic electrical polarization caused by a small shift in the position of some of their atoms that occurs below a critical point called the Curie temperature. This polarization can be switched by an external electric field, an effect exploited in some computer memory devices.


A simulated polarization pattern (top left), polarization vectors within the simulation (top right), and polarization patterns visualized using transmission electron microscopy (bottom left) and piezoresponse force microscopy (bottom right) in the ferroelectric material barium titanate.

Reproduced from Ref. 1 © 2014 American Physical Society

By explaining the origin of puzzling polarization patterns previously seen in a ferroelectric material called barium titanate, Rajeev Ahluwalia and Nathaniel Ng at the A*STAR Institute of High Performance Computing in Singapore and colleagues have stumbled on a way to ‘write’ polarization patterns in nanoscale ferroelectric materials1.

Ferroelectric crystals contain a patchwork of nanoscale ‘domains’, each with a different intrinsic polarization. While an understanding of how these domains form would help to develop reliable applications for ferroelectric materials, two different imaging techniques previously revealed contradictory results about the domains in barium titanate. Ahluwalia’s team therefore set out to solve this puzzle.

One technique — transmission electron microscopy (TEM) — which uses a beam of electrons to probe a crystal’s properties, suggests that the domains comprise long strips arranged in four quadrants, where the net polarization in each quadrant points inward or outward from the surface. The other technique — piezoresponse force microscopy (PFM) — also reveals a quadrant formation, but the polarizations are parallel to the surface so that the overall polarization of the crystal forms a closed loop.

Ahluwalia and his colleagues hypothesized that the TEM’s electron beam changes the polarization pattern in the sample. PFM, in contrast, uses a sharp tip to detect deformations in the material caused by a localized electric field.

The scientists developed a theoretical model, which revealed that an increase in electron density in the crystal produced the same polarization pattern that they observed with TEM. They also calculated that the radial electric field created by an electron beam could generate other distinctive features of this pattern.

Under normal conditions, an electron beam might not alter the domains. But if the beam is strong enough to heat the sample above the Curie temperature, the material loses its intrinsic polarization. As it cools, the radial electric field induced by the electron beam shapes how the domains reform.

The team’s discovery serves as a warning that electron beam techniques could alter the very domains that researchers are seeking to measure. However, electron beams could be used to deliberately alter polarization patterns in ferroelectric materials, something that is potentially useful for the next generation of memory devices with higher storage densities, says Ahluwalia.

The A*STAR-affiliated researchers contributing to this research are from the Institute of High Performance Computing

Associated links

Journal information

Ahluwalia, R., Ng, N., Schilling, A., McQuaid, R. G. P., Evans, D. M. et al. Manipulating ferroelectric domains in nanostructures under electron beams. Physical Review Letters 111, 165702 (2013).

A*STAR Research | ResearchSEA News
Further information:
http://www.researchsea.com

Further reports about: A*STAR Computing Ferroelectric Science TEM Technology materials polarization temperature

More articles from Information Technology:

nachricht Engineers develop new methods to speed up simulations in computational grand challenge
27.03.2015 | University of California - San Diego

nachricht Sensor cable monitors fences of all kinds and can even detect low-level drone fly-bys
25.03.2015 | Universität des Saarlandes

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Experiment Provides the Best Look Yet at 'Warm Dense Matter' at Cores of Giant Planets

In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...

Im Focus: Energy-autonomous and wireless monitoring protects marine gearboxes

The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.

As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...

Im Focus: 3-D satellite, GPS earthquake maps isolate impacts in real time

Method produced by UI researcher could improve reaction time to deadly, expensive quakes

When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.

Im Focus: Atlantic Ocean overturning found to slow down already today

The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe. 

Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...

Im Focus: Robot inspects concrete garage floors and bridge roadways for damage

Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.

From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

10. CeBiTec Symposium zum Big Data-Problem

17.03.2015 | Event News

 
Latest News

Two Most Destructive Termite Species Forming Superswarms in South Florida

27.03.2015 | Agricultural and Forestry Science

ORNL-Led Team Demonstrates Desalination with Nanoporous Graphene Membrane

27.03.2015 | Materials Sciences

Coorong Fish Hedge Their Bets for Survival

27.03.2015 | Ecology, The Environment and Conservation

VideoLinks
B2B-VideoLinks
More VideoLinks >>>