Century-Old Understanding of Light Challenged by New Finding
Researchers have overturned a 180-year-old assumption about how light interacts with matter, revealing a meaningful role for the magnetic component of light – previously considered a secondary effect. The findings, published in Scientific Reports, suggest a pathway to more precise control of light and matter with potential implications for advancements in sensing, memory, computing, and spintronics.
For nearly two centuries,the prevailing understanding,rooted in Faraday’s electromagnetic theory,held that light primarily interacted with matter through its electric field,influencing the charge of electrons. Though, this new research demonstrates that the magnetic field of light exerts a “first-order effect,” directly interacting with an electron’s spin.
“What we’ve found is that the magnetic part of light has a first-order effect, it’s surprisingly active in this process,” researchers stated.
The breakthrough centers on the principle that electrons possess both charge and spin. Researchers found that circularly polarized light – light where the electric field rotates in a circle - can exert a torque on the spin of an electron.
“You can, in very general terms, imagine the electron’s spin as a tiny charge that spins about its axis, almost like a miniature top,” explained researcher Marco Capua. “In order to interact with the ‘spinning electron’ and divert the direction of its spin axis, the magnetic field that interacts with it also needs to “spin,” namely, it needs to be circularly polarized.”
Capua further clarified the interplay: “the electrical field exerts a linear force on the charge while a ‘spinning’ circularly polarized magnetic field exerts a torque on the spin of the electron.”
This discovery could enable scientists to control magnetic data directly with light, according to electrical engineer Benjamin Assouline. It also holds promise for innovations in quantum computing, potentially leading to higher-precision control of spin-based quantum bits, and advancements in spintronics – a field utilizing electron spins for data storage and manipulation.
The research serves as a reminder that even well-established scientific models may hold undiscovered properties, leaving room for further exploration and innovation in the realm of light and electromagnetic phenomena.
