Highly Efficient Opto-Magnetic Control of Magnetization in Nanofilms

Researchers at Tohoku University have made a significant breakthrough in opto-magnetic technology. They have demonstrated an opto-magnetic torque that is approximately five times more efficient than that of conventional magnets. The study was published in Physical Review Letters.

When circularly polarized light is incident perpendicular to the surface of a nano-thin film of cobalt-platinum alloy, which consists of cobalt and platinum, an opto-magnetic torque is generated (red and blue vectors) that changes the magnetization direction (black vector). The opto-magnetic torque consists of components out-of-plane (red vector) and in-plane (blue vector). Image Credit: Nukui et al.

The study, led by Professor Shigemi Mizukami, Assistant Professor Satoshi Iihama, and Mr. Koki Nukui, has important implications for the development of light-based spin memory and storage technologies.

Opto-magnetic torque is a method used to generate force on magnets, allowing for more efficient reorientation using light. The research team developed alloy nanofilms containing up to 70 % platinum dissolved in cobalt, demonstrating that platinum's relativistic quantum mechanical effects significantly enhance magnetic torque. The study attributes this increase to relativistic quantum mechanical interactions and electron orbital angular momentum induced by circularly polarized light.

This advancement enables the same opto-magnetic effect to be achieved with only one-fifth of the previously required light intensity, contributing to the development of more energy-efficient opto-magnetic devices. The findings not only support the design of high-efficiency spin memory and storage systems that use light for data writing but also provide new insights into the role of electron orbital angular momentum in metallic magnetic materials.

These improvements could result in faster and more energy-efficient devices in the future.

Shigemi Mizukami, Professor, Tohoku University

The study aligns with the growing interest in opto-electronic fusion technologies, which integrate optical and electronic methods for future applications. It marks a significant step in using light and magnetism to control nanomagnetic materials.

Journal Reference:

Nukui, K., et al. (2025) Light-Induced Torque in Ferromagnetic Metals via Orbital Angular Momentum Generated by Photon Helicity. Physical Review Letters. doi.org/10.1103/PhysRevLett.134.016701

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type
Submit

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.