Researchers at Cornell University used ultrafine lasers to enhance the magnetic properties of materials at effective temperatures

Using a precisely tuned ultrafast laser, a Cornell University researcher has shown that the atomic structure of yttrium titanate can be altered to stabilize its magnetism at temperatures three times higher than before - a promising discovery for applications in quantum computing and other next-generation devices.

To develop faster, more efficient types of computers, scientists are looking for materials with quantum properties that can work at ambient temperatures. Being able to control magnetism using laser pulses - which depend on microscopic interactions between electron spins - holds the promise of energy saving, high-frequency computers and digital memory.

Ankit Disa '10, an assistant professor of applied physics and engineering physics, is the lead author of the book "YTiO3 Photohigh-temperature Ferromagnetism," published May 3 in Nature.

Collaborators at Disa and the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, found that by using pulses of light at different frequencies in a specially designed terahertz laser source, they could alter the atomic structure of yttrium titanate in different ways -- sometimes significantly enhancing magnetism as the temperature scale improved exponentially.

At other frequencies, however, magnetism is not as strong or does not change.

"The results of our work are encouraging and exciting for many reasons," Disah said. "We were able to demonstrate the ability to manipulate the structure of the material, which helps us understand the structure-property relationship in the material. Secondly, from a technical point of view, we found that using pulses of light several hundred femtoseconds long -- or less than a millionth of a second -- we could change the magnetic state of the atom."

This could allow new types of calculations - based on the spin of electrons, rather than the charge - to run several orders of magnitude faster and more efficiently than existing computing techniques. But controlling magnetism is challenging, Disa said.

"To control magnetism, you have to apply a magnetic field," he said. "This often requires bulky electromagnetic coils and is difficult to do on a microscopic scale. The fact that we showed how to do this with light, and can improve the properties of existing magnets in this way, helps push such technologies forward."

Disa plans to further develop experimental installations and collaborate with material design experts (researchers who are creating new materials that can be layered atom by atom) to explore new ways of using light to optimize material properties, including magnets, electronic materials and superconductors.

The experimental work for the research project was carried out at the Max Planck Institute. Other collaborators are from Harvard University, the Leibniz Institute for Solid State and Materials Research and the University of Oxford.

Source: Laser Net