New Theory to Explore Atomic and Magnetic Vibrations at the Nanoscale

Atoms inside materials vibrate in organized patterns called phonons, that among other aspects, transport heat and influence structural stability. In magnetic materials, waves of magnetic energy, magnons, determine how magnetic information is stored and transferred. These two processes are fundamental to the performance of solid-state devices, such as memories in computers or cellular phones, but the understanding of their behavior at the atomic scale has been a longstanding challenge.

The researchers José Ángel Castellanos-Reyes, Paul Zeiger, and Ján Rusz have addressed this problem and developed a new theoretical method called TACAW (Time Auto-Correlation of Auxiliary Wave functions). TACAW is a groundbreaking method to simulate how high-energy electrons interact with thin samples of materials. By tracing energy loss and gain processes, TACAW provides precise insights into the properties of phonons and magnons at the nano- and atomic scale, bridging the gap between theoretical predictions and experimental observations.

What makes TACAW unique, and is done for the first time now, is the ability to describe how magnons can be detected and studied using transmission electron microscopes. It also excels in addressing complex phenomena such as multiple electron-sample interactions and the effects of temperature, outperforming traditional approaches. Tested on materials like silicon, boron nitride, and iron, TACAW has delivered accurate results that align closely with experimental data.

“This method allows us to explore the intricate vibrations and magnetic waves inside materials at a level of detail previously unattainable. With TACAW, we’re contributing to designing materials for the technologies of tomorrow”, says Ángel Castellanos, postdoc at the Department of Physics and Astronomy and first author of the paper.

TACAW holds much promise as a research tool. By providing a deeper understanding of atomic vibrations and magnetic waves, the method is expected to contribute to breakthroughs in more efficient heat management in electronics, and faster, more reliable data storage.

The research was published in the scientific journal Physical Review Letters and the researchers emphasize that this publication is only the beginning.

“Future studies aim to apply TACAW to complex materials, refine experimental validation, and guide new experimental techniques. As it evolves, TACAW is poised to become a cornerstone in analysing Transmission Electron Microscopy data, unlocking new ways to design and understand the materials that shape our technological future.”, says Paul Zeiger, researcher at the Department of Physics and Astronomy.