Correlation and exchange energies of a quantum Hall ferromagnet with ν= 13 in the strong interaction regime

Collective spin excitations were utilized to probe many-particle energies of strongly correlated quantum Hall ferromagnets (FMs) at 13≤ν≤1. For this purpose, experiments on inelastic light scattering and polarized photoluminescence (PL) were performed on a MgZnO/ZnO heterostructure, containing a high-mobility two-dimensional electron system with the Wigner-Seitz parameter rs≈11. The dispersion of the Larmor spin exciton was utilized to extract the spin stiffness, which was found to have maxima at ν=13, ν=1, and to be strongly suppressed at intermediate filling factors. Measurements of circularly polarized PL helped to confirm a FM configuration of the system. In the close vicinity of ν=13, a hybrid spin-density excitation was discovered, the energy of which enables us to probe the correlation energy of the Laughlin liquid. The measured correlation and exchange energies at ν=13 and rs1 turned out to be much less suppressed by the Landau level mixing than the exchange energy at integer filling factors. The same answer follows from the calculations performed using the exact diagonalization method. © 2024 American Physical Society.