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Use a microscope like a shovel? Researchers retrieve it



<a rel = "lightbox" href = "https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2019/5c4c41ff27ccd.jpg" title = "TAFM of BiFeO3 / SrRuO3 / DyScO3 Thin Film Heterostructure Credit: Research of the National Academy of Sciences (2019). DOI: 10.1073 / pnas.1806074116 ">
<img src = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2019/5c4c41ff27ccd.jpg" alt = "Use a shovel like a shovel?" Researchers extracted it from TAFM on a thin layer heterostructure of BiFeO3 / SrRuO3 / DyScO3 Regards: Proceedings of the National Academy of Sciences (201
9) DOI: 10.1073 / pnas.1806074116

The use of a known tool in a way that was never intended to be used reveals a whole new method of material research, UConn researchers report in the National Academy of Sciences reports . Their specific finds may someday create more energy-efficient computer chips, but the new technique itself can open new discoveries across a wide range of products.


Atomic Force Microscopes (AFM) slide ultra-sharp tops in the materials so close, but never touch the surface. The tip can be felt when the surface is to detect electrical and magnetic forces produced by the material. Methodically going back and forth, the researcher can plot the surface properties of the material in the same way that the surveyor methodically passes through a piece of land to map the territory. ASMs can map the holes, protrusions, and material properties on a scale that is thousands of times smaller than a grain.

ACMs are designed for surface testing. Most of the time, the user is trying very hard not to pick up the material with the tip, as this may damage the surface of the material. But sometimes it happens. Several years ago, aspirant Yassin Koutes and Justin Luria, a postdoctoral student, are studying solar cells in Brian Hugh's Laboratory of Materials Science and Engineering Professor, accidentally penetrating their sample. Initially, they thought it was an irritating mistake, they noticed that the properties of the material looked different when Quite clutched the top of the AMS deep into the ditch she had accidentally dug.

Coutes and Luria did not pursue him. But another graduate, James Stefs, was inspired to take a closer look at the idea. What would happen if you intentionally used the top of the ASM like a chisel and dug into material, he asked? Will it be able to plot the electrical and magnetic properties layer by layer, constructing a 3-D picture of the properties of the material in the same way it is applied to the surface in 2-D? And will the properties look different in the material?

The answers, Steffes, Huey and their colleagues report in PNAS yes and yes. They are buried in a sample of bismuth ferrite (BiFeO3), which is multiferrous at room temperature. Multi-ferroids are materials that can have multiple electrical or magnetic properties simultaneously. For example, bismuth ferrite is an antiferromagnet – reacts to magnetic fields, but generally does not show a north or south magnetic pole – and a ferroelectric, which means there is a switchable electric polarization. Such ferroelectric materials usually consist of small plots called domains. Each domain is like a cluster of batteries, all of their positive terminals are aligned in the same direction. Clusters on both sides of this area will be directed in a different direction. They are very valuable for computer memory, because the computer can reverse the domains, "write" on the material using magnetic or electric fields.

When a material scientist reads or writes information about a piece of bismuth ferrite, they can normally do so. I only see what happens on the surface. But they would like to know what is happening below the surface – if it is understood, it may be possible to inject the material into more efficient computer chips that work faster and use less energy than those available today. This can lead to a big difference in total energy consumption in society – already 5% of all US electricity consumption goes to working computers.

To find out, Steffes, Huey and the rest of the team have used the AFM board carefully digging through a bismuth ferrite film and mapping the interior, piece by piece. They have found that they can make a map of the individual areas all the way down, exposing patterns and properties that have not always been apparent on the surface. Sometimes the domain is narrowed down until it disappears or is divided into y-form or merged with another domain. No one has ever seen inside the material that way. It was a revelation similar to a 3-D CT bone scan when you were previously able to read only 2-D X-rays.

"There are about 30,000 AFMs installed worldwide, some of whom will experience [3-D mapping with] AFM in 2019, as our community realizes that they have just scratched the surface all the time," Huey predicts. He also believes that more labs will buy AFM now if it is proven that 3-D mapping works for their materials and some microscopy makers will start designing AFMs specifically for 3-D scanning

Steffes has completed UConn with PhD, and now works at GlobalFoundries, a computer chip maker, Intel researchers, muRata and others they are also intrigued by what the group has discovered for the bismuth ferment as they are looking for new materials to make the next generation of computer chips.The Huey team, meanwhile, uses AFMs to dig all kinds of materials from concrete to bone

"Working with academic and corporate partners, we can use our new look to understand how to improve Engineer these materials to use less energy, optimize their work, and improve their reliability lifetime – these are examples of what material scientists strive to do every day, says Huey.


See also:
Ratio between the structure and the magnetic properties of ceramics

More Information:
James J. Steffes et al., Ferroelectric Thickness Zoom in BiFeO3 by Atomic Tomography Microscopy Research by the National Academy of Sciences (2019). DOI: 10.1073 / pnas.1806074116

Journal Number:
Notifications of the National Academy of Sciences

Submitted by:
University of Connecticut


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