We use inelastic neutron scattering (INS) and angle-resolved photoemission spectroscopy (ARPES) to study the impact of Li doping on the semiconducting altermagnet α-MnTe. Introducing Li results in a spin reorientation from in-plane to out-of-plane direction and increases the density of itinerant carriers. While our ARPES measurements do not indicate any notable doping-induced changes in the electronic band structure or the magnitude of the altermagnetic band splitting, our INS measurements reveal an abrupt carrier-induced decrease in the spin wave lifetime near the zone boundary at high energies. This finding is consistent with a new magnon decay channel driven by doping-induced subtle changes in the band structure and enhanced interactions between Mn2+ local moments and itinerant electrons. By extracting the local dynamic susceptibility from INS spectra and applying the total moment sum rule, we find that both undoped and Li-doped α-MnTe exhibit the full expected Mn2+ local moment of ≈5.9μB with S=5/2. These findings suggest that α-MnTe hosts robust local-moment altermagnetism which shows a breakdown at high energies upon addition of itinerant carriers, highlighting the importance of carrier-spin coupling in magneto-transport and spin dynamic properties of altermagnets even in the dilute-carrier limit.
@article{arxiv.2512.00747,
title = {Evidence for itinerant electron-local moment interaction in Li-doped $\alpha$-MnTe},
author = {Tingjun Zhang and Steven J. Gomez Alvarado and Sijie Xu and Thomas Hulse and Travis J. Williams and Xiaoping Wang and Junhong He and Matthew B. Stone and Colin Sarkis and Feng Ye and Zhaoyu Liu and Jinyulin Li and Aparna Jayakumar and Zehao Wang and Yaofeng Xie and Ching-Wu Chu and Liangzi Deng and Emilia Morosan and Ming Yi and Pengcheng Dai},
journal= {arXiv preprint arXiv:2512.00747},
year = {2026}
}