In a groundbreaking study, Cornell Engineering researchers have unveiled a remarkable method to manipulate materials at an atomic level. By bombarding a synthetic thin film with ultrafast infrared light pulses, they have triggered a phenomenon where the material's lattice oscillates—effectively ‘breathing’—billions of times per second. This strain-driven dynamic could pave the way for revolutionary advancements in switching electronic, magnetic, and optical properties of materials.

The Science Behind the 'Breathing' Effect

Published on September 12 in Physical Review Letters, this research showcases the potential of using low-frequency infrared light to induce strain in materials, a method that has been relatively unexplored compared to traditional stretching methods.

Nicole Benedek, an associate professor of materials science and engineering, noted that manipulating materials with light presents a unique set of challenges due to the complexity of light-matter interactions. Her computational theories helped identify the optimal light frequency and experimental parameters necessary to achieve a reversible ‘dynamic’ strain.

How Ultrafast Light Pulses Work

The researchers discovered that firing terahertz light in picosecond bursts—matching the low frequencies of phonons, the vibrational waves in crystals—could achieve the desired atomic deformation. Andrej Singer, another associate professor on the project, likened the movement of atoms to a swing: "If you swing it at the right frequency, you can increase the amplitude of that atom, leading to rapid lattice expansion."

Choosing the Right Material

The team decided to use lanthanum aluminate, a material that may seem dull at first glance. Benedek explained that its seemingly mundane properties made it perfect for their experimental needs, aiming for simplicity amidst a complex theoretical landscape. However, this ‘boring’ material proved to be much more intriguing than expected!

Unexpected Outcomes

With the material synthesized by Darrell Schlom through advanced techniques, the researchers assessed their results using a free-electron laser at Stanford’s SLAC National Accelerator Laboratory. Surprisingly, the experiment revealed that the ultrafast light pulses not only induced the expected strain but also permanently enhanced the structural integrity of lanthanum aluminate.

New Possibilities Unlocked

The findings unlock exciting potential for material innovation. By cleverly applying low-frequency light, scientists can theoretically switch between different material states, enabling rapid transitions in electronic and magnetic properties, and even structural changes that could lead to superconductivity.

Singer summed it up by saying, "Combining theory with synthesis and characterization gives us powerful insights into how light interacts with complex oxide materials, allowing us to access unique properties beyond conventional methods."