Scientists in Germany and the United States have made a groundbreaking breakthrough in the field of material physics. Through their collaborative research, they have demonstrated the ability to control the magnetic state of a specific material, α-RuCl3, by placing it within an optical cavity. It was found that the mere presence of the cavity’s vacuum fluctuations can transform the material’s magnetic order from a zigzag antiferromagnet into a ferromagnet. This achievement, detailed in the published article in npj Computational Materials, opens up new possibilities for manipulating materials using light without the need for intense lasers.
In recent years, the utilization of intense laser light has been a popular approach to modifying the properties of magnetic materials. By carefully designing the characteristics of laser light, researchers have successfully altered the electrical conductivity and optical properties of various materials. However, this method requires continuous stimulation with high-intensity lasers, which often results in the material heating up. To overcome this challenge, scientists have been eager to find alternative ways to achieve similar control over materials using light, but without the drawbacks of intense lasers.
Researchers from the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg, Germany, Stanford University, and the University of Pennsylvania in the United States have devised a different strategy. They have demonstrated that the magnetic properties of the real material α-RuCl3 can be changed within a cavity without the use of laser light. The team revealed that the mere presence of the cavity alone could transform the material from a zigzag antiferromagnet into a ferromagnet. Surprisingly, the researchers discovered that even within a seemingly dark cavity, α-RuCl3 can sense changes in the electromagnetic environment and adjust its magnetic state accordingly.
This transformative effect is solely due to quantum mechanics, as the vacuum inside the cavity is never truly empty according to quantum theory. The fluctuations in the light field cause particles of light to momentarily appear and disappear, which consequently impacts the properties of the material. Emil Viñas Boström, the lead author and a postdoctoral researcher in the MPSD Theory Group, explains that the confinement of the electromagnetic field by the optical cavity enhances the effective coupling between the light and the material. The team’s research highlights the significance of engineering the vacuum fluctuations of the cavity’s electric field, as it can induce substantial changes in the magnetic properties of a material.
Unlike the traditional approach that requires light excitation, the technique employed by the researchers avoids the issues associated with continuous laser driving. This study represents the first successful demonstration of cavity control over magnetism in a real material. Previous research has explored cavity control of ferroelectric and superconducting materials, but this latest achievement expands the possibilities even further. The researchers envision that the design of specific cavities will enable them to explore new and elusive phases of matter, providing a deeper understanding of the intricate relationship between light and matter.
The collaborative research conducted by scientists in Germany and the United States has shown tremendous potential in the field of material physics. The ability to manipulate the magnetic properties of a material solely by placing it within an optical cavity opens up new avenues for research and exploration. The shift away from intense laser light towards light-based control offers a more efficient and practical approach. As scientists continue to engineer and develop specific cavities, it is anticipated that novel phases of matter will be discovered, leading to further advancements and a greater understanding of the intricate interplay between light and matter.