Chiral magnon diode effect

Reciprocity–the equivalence between forward and reverse processes–is a fundamental consequence of time-reversal and spatial symmetries in condensed-matter systems. Breaking this reciprocity gives rise to directional transport phenomena such as the diode effect, which forms the basis of modern electronics. Here we report a magnonic analogue of this behavior in the chiral-polar antiferromagnet NiCo₂TeO₆, where circularly polarized terahertz radiation reveals a clear non-reciprocal magnon response even in the absence of an external magnetic field. Simulations based on the Landau-Lifshitz-Gilbert equation show that left- and right-circularly polarized light selectively excite clockwise and counterclockwise spin-precession modes, respectively, leading to distinct spectral characteristics that mimic a diode-like correspondence between opposite electric-polarization states (+P/−P). Experimentally, the magnon absorbance A_LCP(+P) coincides with A_RCP(−P), directly confirming the predicted magnonic diode effect. Under applied magnetic fields, non-reciprocal components remain visible in the spectra, demonstrating that the intrinsic chiral-polar coupling persists even when external perturbations are introduced. These findings establish NiCo₂TeO₆ as a model platform for exploring diode-like spin dynamics and light-induced reciprocity breaking in magnetically chiral systems.