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Using an atomic force microscope such as a nanoscopic shovel



January 27, 2019

(Nanowerk News) The use of a family tool in a way that was never used opens a new method to explore materials, reports the researchers at UConn Acts of the National Academies of Science ("Scale of ferroelectricity thickness in BiFeO3 for the atomic tomographic microscopy.) Their specific results could be created, at some point, much more effective computer files, but the new technique could open new discoveries in a wide range of products.

Atomic force microscopes (AFM) drag an ultra-high through the materials, so narrow but without touching the surface. The tip can feel where the surface is, detecting electrical and magnetic forces produced by the material. Through the method of returning, a researcher can draw surface properties of a material in the same way that a surveyor passes methodically through a terrain to map the territory. AFM can map holes, protrusions, and properties of a material on a scale of thousands times smaller than a grain of salt. Atomic force tomographic microscopy Atomic force tomographic microscopy of BiFeO3/ SrRuO3/ DyScO3 thin layer heterostructure. (© PNAS)

The AFM are designed to investigate surfaces. Most of the time, the user tries to do so with the tip, since this can damage the surface of the material. But sometimes it happens. A few years ago, the graduate student Yasemin Kutes and Justin Luria, a student of solar cells in the scientific materials laboratory and engineer Brian Huey, accidentally excavated in their sample. Initially, he thought it was an irritating mistake, they realized that the material's properties seemed different when Kutes snapped the tip of the AFM on the bench that had accidentally dug.

Kutes and Luria did not chase him. But another postgraduate student, James Steffes, was inspired to look more closely at the idea. What would happen if you intentionally use the end of an AFM as a chisel, and dug in a material, you ask? Could you map the electrical and magnetic properties by layer, creating a 3D image of the properties of the material in the same way that it assigned the surface to 2D? And the properties will go to the depths of a different material?

The answers, Steffes, Huey and his colleagues, report in PNAS, are yes and yes. They dig in a sample of bismuth ferrite (BiFeO3), which is a multifarious ambient temperature. Multiferroics are materials that can have multiple electrical or magnetic properties at the same time.

For example, the bismuthian ferrite is antiferromagnetic: it responds to the magnetic fields, but generally it does not have a magnetic north or south pole and ferroelectric, that is, it has a commutable electric polarization. These ferroelectric materials are usually formed by small sections, called domains. Each domain is like a set of batteries that all have their positive terminals aligned in the same direction. Clusters on either side of this domain will be indicated in another direction. They are very valuable for the computer memory, because the computer can invest the domains, "write" in the material, using magnetic or electric fields.

When a material scientist reads or writes information about a bismuth ferrite piece, they can usually only see what happens on the surface. But I would love to know what happens under the surface, if this were understood, it might be possible to start the material in more efficient computer tabs that work faster and less energy than today's. This could make a big difference in the global energy consumption of the company, since 5 percent of all electricity consumed in the U.S. is directed to computers in operation.

To find out, Steffes, Huey and the rest of the team used an AFM tip to dig through meticulously through a bismuth ferrite film and draw the interior piece the piece They found that they could assign a map to individual domains until the end, exposing patterns and properties that were not always apparent on the surface. Sometimes a domain was reduced until it vanished or divided into a Y form, or merged with another domain. No one has ever been able to see inside the material this way. It was revealing, such as observing a 3D three-dimensional tomography 3D scanner when you could only read X-ray 2D before.

"Around the world, there is something like 30,000 AFM already installed, a large fraction of these will try [3D mapping with] AFM in 2019, as our community realizes that they have just been scratching the surface all this time, "predicts Huey. He also believes that more laboratories will buy AFM now if it is shown that 3D mapping works for their Materials, and some microscope manufacturers will begin designing AFM specifically for 3D scanning.

Steffes graduated from UConn with his Ph.D. and now he works at GlobalFoundries, a manufacturer of computer chips. Intel researchers, MuRata and other sites are also intrigued with what the group discovered about the bismuth ferrite, as they are looking for new materials to make the next generation of computer files. Meanwhile, the Huey team is using AFM to excavate all types of materials, from concrete to the right, to a large number of computer components.

"Working with academic and corporate partners, we can use our new perspective to understand how to improve the engineering of these materials to use less energy, optimize their performance and improve their reliability and useful life. These are examples of the material that scientists strive to do every day, "says Huey.


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