Investigating the yellow exciton series of Cu2O at ultrahigh magnetic fields

Hydrogen-like systems in ultra-high magnetic fields are of significant interest in interdisciplinary research. Previous studies have focused on the exciton wavefunction shrinkage under magnetic fields down to artificial crystal lattices, while further compression toward the natural crystal lattice remains experimentally challenging. Here we report magneto-absorption measurements on the yellow-exciton series in cuprous oxide using pulsed magnetic fields up to 500 T. The strong low energy absorption features are assigned to the spin Zeeman split 2 p 0 and 3 p 0 exciton states, resolving existing ambiguities regarding their quantum number assignments. The high-field data provides an exciton reduced effective mass of 0.415 ± 0.01 m e . Intriguingly, above 300 T, the energy evolution of the 2 p 0 state deviates from the hydrogen model, accompanied by a sudden increase in the exciton linewidth. We attribute this to a non-parabolic effect on the valence band due to the band mixing of the valence band top and the split-off band through the large Landau quantization energy.