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LASSP -  Laboratory of Atomic and Solid State Physics

Cornell Laboratory for Atomic and Solid State Physics

Dan Ralph's Group Contributes to Creation of Smallest Etch A Sketch

 Dan Ralp Co-authored “Local Photothermal Control of Phase Transitions for On-Demand Room-Temperature Rewritable Magnetic Patterning,” published April 21 in Advanced Materials.

Antonio Mei, a postdoctoral researcher in the group of Darrell Schlom, the Herbert Fisk Johnson Professor of Industrial Chemistry in the Department of Materials Science and Engineering, used molecular-beam epitaxy to stack atomically thin layers of iron rhodium in a strategic arrangement, so that its ferromagnetic and antiferromagnetic phases both became stable at room temperature.

“The sample is equally happy having either strong magnetism or no net magnetism,” Schlom said, “like a teeter-totter that is equally stable resting on the ground with its left seat or its right seat.”

Magnetic patterns are traditionally formed on materials by first configuring a ferromagnetic material’s electrons all in one direction and then configuring selected regions in the opposite direction. But with iron rhodium, the material can begin as antiferromagnetic, and regions can be heated to be ferromagnetic, with those regions remaining strongly magnetic at room temperature.

“It’s like an Etch A Sketch,” said Schlom, referring to a toy in which images can be drawn onto a screen and erased, “where slight heating does the writing and if you wish, slight cooling does the erasing.”

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