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
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
Stanford researchers create new special-purpose computer that may someday save us billions
21.10.2016 | Stanford University
New 3-D wiring technique brings scalable quantum computers closer to reality
19.10.2016 | University of Waterloo
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences