- A theoretical model indicates that the magnetic field of light directly influences the Faraday effect.
- The calculated contribution reaches ~17% in visible light and up to 70% in infrared for TGG.
- The study is based on the Landau-Lifshitz-Gilbert equation and is published in Scientific Reports.
- Possible applications: advanced optics, spintronics and quantum technologies in Europe.
Research into the interaction between light and matter has added an unexpected piece: the magnetic field of light It also contributes to the Faraday effect.not only its electrical component, according to a study signed by a team from the Hebrew University of Jerusalem.
The results, Published on November 20, 2025 in the magazine Scientific ReportsThey support this with a theoretical model that Light can generate a magnetic torque in materialsquantifying its role with significant figures: approximately 17% of the rotation in the visible range y up to 70% in infrared.
What changes in our view of the Faraday effect?
During almost two centuries It was assumed that the rotation of the plane of polarization when passing through a magnetized medium came fromEssentially, from the interaction between the electric field of light and the charges of the material.
El New work argues that the magnetic part of the electromagnetic field is not passive: induces a internal magnetic torque in the middle, analogously to a constant external magnetic field, and its effect is not residual under certain spectral conditions.
Methodology and theoretical model
The team, led by Amir Capua and Benjamin Assouline, employs the Landau-Lifshitz-Gilbert equation to describe the dynamics of electron spins in magnetic materials subjected to the action of the magnetic field of light.
The formulation shows how The oscillating magnetic component couples to the spins and exerts a measurable torqueIn their validation, the authors chose a reference crystal in magneto-optics: the gallium-terbium garnet (TGG), widely used to study and calibrate the Faraday effect.
Quantitative results in TGG
Applying the model to the TGG, the magnetic contribution of light explains about one 17% of the polarization rotation in the visible spectrum and can rise to 70% in the infrared, magnitudes that force a review of the usual interpretations.
The relative weight of each contribution depends on the wavelength and the optical and magnetic properties of the material, suggesting design scope for optimization magneto-optical devices in different bands.
Implications for optics, spintronics and quantum technologies in Europe
In applied optics, a deliberate control of light-induced magnetism It would allow the adjustment of optical isolators, Faraday modulators, and field sensors with new strategies based on spectral engineering.
In spintronics, harnessing the magnetic component of the beam to drive the spin information processing It could facilitate more efficient memories and ultra-fast switching schemes without electrical contact.
For quantum technologies, light-magnetism coupling points to pathways for manipulating spin-based qubits, with interest for European ecosystems focused on integrated photonics and coherent control of magnetic states.
What remains to be verified
Although the evidence presented is theoretical, the work outlines a plausible experimental plan: highly sensitive magneto-optical metrology, rigorous spectral calibration, and the use of highly stable light sources to unequivocally separate the magnetic contribution from the electrical one.
European photonics infrastructures and university laboratories could address this experimental validationextending the analysis to other magneto-optical materials, including integrated waveguides and resonators.
Key questions of the study
Who signs off on the work? A team from the Hebrew University of Jerusalem, with Amir Capua and Benjamin Assouline at the helm.
Where is it published? In the open access journal Scientific Reports, which facilitates review and reproduction by other groups.
What material was analyzed? TGG crystal, a reference in studies of the Faraday effect due to its high magneto-optical response.
Why does it matter? Because it shows that light, in addition to its electrical action, has a direct magnetic influence and quantifiable on the subject, with an impact on device design.
The proposal adds a layer of precision to the understanding of Faraday effectIt integrates the role of the magnetic field of light with numbers and a solid theoretical framework, and opens a practical way to exploit this contribution in photonic and quantum applications of particular interest to the European research and industrial fabric.
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