Quantum mechanics governs the behavior of electrons within magnetic materials, with their spins dictating the magnetic properties of the material. Now, a team of researchers from JILA, led by Margaret Murnane and Henry Kapteyn, has made a groundbreaking breakthrough in controlling these spins with exceptional precision. By harnessing the power of extreme ultraviolet high-harmonic generation (EUV HHG) as a probe, the team has opened new possibilities for revolutionizing electronics and data storage.
The JILA team, in collaboration with universities in Sweden, Greece, and Germany, focused their research on a Heusler compound, a unique mixture of metals that behaves as a unified magnetic material. Specifically, they examined a compound comprised of cobalt, manganese, and gallium. By exciting the compound with a femtosecond laser, the researchers induced changes in its magnetic properties and tracked the spin re-orientations using EUV HHG.
The novelty of the JILA team’s work lies in their ability to tune the color of the EUV HHG probe light, allowing for unparalleled precision in tracking spin changes. Unlike previous studies that only measured signals at a few different colors, this research pioneered the tuning of HHG light probes across the magnetic resonances of each element within the compound. This meticulous approach enabled the researchers to track spin changes with a precision down to femtoseconds.
To validate their findings, the JILA researchers collaborated with theorist Mohamed Elhanoty of Uppsala University. Elhanoty’s theoretical models of spin changes were compared with the experimental data, showcasing a strong correspondence between theory and reality. This agreement sets a remarkable new standard in the field, demonstrating the power of combining experimental and computational approaches.
In order to delve deeper into the spin dynamics of the Heusler compound, the JILA team introduced a cutting-edge tool: extreme ultraviolet high-harmonic probes. By focusing laser light into a tube filled with neon gas, the team generated these specialized probes. The electric field of the laser pulled electrons away from their atoms and then propelled them back, resulting in bursts of light at a higher frequency than the initial laser. These bursts, tuned to resonate with the energies of cobalt and manganese, allowed for the measurement of element-specific spin dynamics and magnetic behaviors.
The JILA researchers discovered that by tuning the power of the excitation laser and the color of their HHG probe, they could determine which spin effects were dominant at different times within the compound. Comparing their measurements with time-dependent density functional theory (TD-DFT), they identified three competing spin effects: spin flips, spin transfers, and de-magnetization. The understanding of these effects provides insights into how spins can be harnessed to enhance the magnetic and electronic properties of materials.
The concept of spintronics, which utilizes the spin of electrons in addition to their charge, opens up new possibilities for faster and more efficient electronic devices. By leveraging the magnetic component of spintronics, these devices could exhibit reduced resistance and thermal heating. The research conducted by the JILA team, in collaboration with Elhanoty and other partners, offers crucial insights into spin dynamics within Heusler compounds, laying the groundwork for leveraging light to manipulate spin patterns.
The JILA researchers have unveiled a new era in quantum spin control with their groundbreaking research on Heusler compounds. By precisely tracking spin changes and achieving correspondence between theory and experiment, they have paved the way for advancements in spintronics and magnetics. This collaboration highlights the power of interdisciplinary research and raises exciting possibilities for the manipulation of spin patterns using light.