{"id":"APP-260617-0001","repo_url":"https://github.com/AbhinavaPSU/Nonreciprocal-axion-polaritons","versions":[{"v":1,"tag":"v1.0.0","commit":"5c1610a0e02629075bb77733cf04e93a09cfd49d","app_publication_id":"app-v1:sha256:5b4cda81f6356ee3c042de6ba0d6ba84bb55dbe9b52d7d31909d3f8142a18234","release_url":"https://github.com/AbhinavaPSU/Nonreciprocal-axion-polaritons/releases/tag/v1.0.0","listed_at":"2026-06-17","title":"Perfect Nonreciprocal Axion-polaritons","authors":[{"name":"Abhinava Chatterjee","affiliation":"Department of Physics, The Pennsylvania State University"},{"name":"Chao-Xing Liu","affiliation":"Department of Physics, The Pennsylvania State University"}],"domain":"condensed-matter-physics","arxiv_id":"2606.04341","tags":["axion-polaritons","nonreciprocity","optical-isolator","topological-materials","axion-electrodynamics","magnon-polaritons"],"paper_summary":"Under appropriate static electric (E₀ ‖ ŷ) and magnetic (B₀ ‖ ẑ) fields applied simultaneously to a dynamical axion insulator, axion-polaritons — hybrid axion-photon collective modes — acquire a nonreciprocal dispersion ω(k) ≠ ω(−k). This arises because the axion-photon coupling is direction-dependent: photons propagating in opposite directions hybridize with the axion with different strengths (g₊ ≠ g₋). Neither field alone is sufficient; the simultaneous breaking of inversion symmetry (by E₀) and time-reversal symmetry (by B₀) produces the term 2𝓔𝓑kω in the quartic dispersion (Eq. 4) that is the microscopic origin of nonreciprocity.\n\nThe paper identifies a special regime of *perfect nonreciprocity* when E₀ = c′B₀: here ω = c′k is an exact solution of the quartic, meaning the right-moving photon is completely decoupled from the axion source while the counter-propagating photon hybridizes strongly — a one-way coupling with no analogue in prior axion-polariton work. This direction-dependent coupling manifests directly as an optical isolator: a finite slab transmits light left-to-right with high efficiency while right-to-left transmission is exponentially suppressed near the axion resonance. The results propose nonreciprocal axion-polaritons as a new experimental probe of axion quasiparticles, with material parameters motivated by GHz-frequency magnon measurements in MnBi₂Te₄."}]}