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 The TU Ilmenau develops tomorrow’s chip technology today
27.04.2017 | Technische Universität Ilmenau

nachricht Five developments for improved data exploitation
19.04.2017 | Deutsches Forschungszentrum für Künstliche Intelligenz GmbH, DFKI

All articles from Information Technology >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>