Altermagnetic photonic crystals
Researchers have developed a photonic platform that demonstrates altermagnetic behavior, a magnetic phase previously only observed in fermionic systems. By using a magnetophotonic crystal, the team achieved momentum-dependent polarization splitting without net magnetization, offering a new path for spin-functional photonic devices.
Why it matters
This discovery provides a new physical platform for manipulating light and spin, which could lead to advancements in high-speed, energy-efficient photonic computing and communication technologies.
Nature Physics ( 2026 ) Cite this article
Altermagnetism is a magnetic phase that combines zero net magnetization with time-reversal-symmetry breaking and momentum-dependent spin splitting, but it has so far been confined to fermionic systems. Here we report a photonic platform capturing the symmetry features of altermagnetism. Using a magnetophotonic crystal with staggered magnetic bias and controlled structural variation, we observe momentum-dependent polarization splitting, spin–momentum locking and vanishing net magnetization in the photonic band structure. By solving Maxwell’s equations, we show that the momentum-dependent splitting is symmetry governed, rather than a consequence of the momentum-independent gyrotropic effect. These results demonstrate a photonic analogue of altermagnetic behaviour and provide a route towards spin-functional photonic devices without net magnetization.
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