Itinerant and Correlated Nature of Altermagnetic MnTe Single Crystal Studied by Photoemission and Inverse-Photoemission Spectroscopies

Occupied and unoccupied electronic states of altermagnetic MnTe(0001) single crystals were studied by photoemission and inverse-photoemission spectroscopies after establishing a reproducible surface cleaning procedure involving repeated sputtering and annealing cycles. The angle-resolved photoemission spectroscopy (ARPES) exhibited a hole-like band dispersion centered at the Γ¯ point, which was consistent with the reported ARPES results and our density functional theory (DFT) calculations with the on-site Coulomb interaction <i>U</i>. The observed Mn 3d↑-derived peak at -3.5 eV, however, significantly deviated from the DFT + <i>U</i> calculations. Meanwhile, the Mn 3d↓-derived peak at +3.0 eV observed by inverse-photoemission spectroscopy agreed well with the DFT + <i>U</i> results. Based on simulations of the spectral function employing an <i>w</i>-dependent model self-energy, we found significant relaxation effects in the electron-removal process, while such effects were negligible in the electron-addition process. Our study provides a comprehensive picture of electronic states, forming a solid foundation for understanding the magnetic and transport properties of MnTe.