Original title: Photonic magnetism and altermagnetism without magnetic materials
Tiancheng Zhang, Lijie Li, Zhuo Liu, Li Lei +6 · September 2026
Magnetism usually comes from the spins of electrons inside magnetic solids. Scientists recently discovered altermagnetism, a new magnetic phase driven by symmetry. Trying to copy this phase using light has been hard. Typical attempts depend on magneto-optic materials, which suffer from built-in frequency limits that restrict optical uses. To solve this, researchers designed optical lattices made entirely of plain, nonmagnetic dielectric materials. They mapped electron spin and magnetic atoms onto properties of light using mathematical symmetry rules. Light moving through these patterned lattices naturally acts as if it is inside a magnet. Their experiments, models, and simulations proved this works at telecom wavelengths near 1550 nm. They produced photonic versions of ferromagnetism, antiferromagnetism, and altermagnetism without any magnetic substances. This demonstrates that symmetry and light-mode coupling alone can recreate magnetism to control light based on spin.
You are trying to make a compass needle point north, but you have no iron. You discover that by arranging wooden sticks in a precise pattern, the compass needle still aligns. In this paper, the researchers create magnetic-like effects for light using only non-magnetic glass, by patterning it in a specific lattice that mimics the symmetry of magnetic materials.
This work shows that magnetic-like behavior can be engineered in ordinary glass structures, removing the need for rare magnetic materials. It could lead to new ways to control light polarization and spin at telecom wavelengths, potentially impacting optical communication and quantum technologies. The approach also opens up magnetic phenomena to any frequency, not just those limited by natural magnetic materials.
The abstract does not discuss practical limitations such as fabrication tolerances, scalability to other wavelengths, or integration with existing photonic devices. The demonstration is at a single telecom wavelength and in a specific lattice geometry. The photonic magnetism is an analog, not actual magnetic interaction, so it may not replicate all electronic magnetic phenomena.
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Photonic magnetism and altermagnetism without magnetic materials — Tiancheng Zhang, Lijie Li, Zhuo Liu et al.
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.