Evolution of the Spin Order in Hall Ferromagnets under the Strong Mixing of Landau Levels and at the Filling Factors 1 ≤ ν ≤ 2

Abstract

An unconventional behavior of the spin order in strongly correlated two-dimensional electron systems based on MgZnO/ZnO heterostructures has been detected in the quantum limit at the filling factors 1 ≤ ν ≤ 2. Under the variation of the filling factor and the orientation of a magnetic field, inelastic light scattering spectra exhibit characteristic transformations of collective spin excitations, which indicate qualitatively different rearrangements of the spin configuration in the system: smooth depolarization at 1 < ν < 3/2 with the formation of spin textures and sharp ferromagnetic instability at a certain filling factor in the range 3/2 < ν ≤ 2. Comparison with the magnetotransport experiments reported in [J. Falson, D. Maryenko, B. Friess, et al., Nature Phys. 11, 347 (2015)] shows that the disappearance of spin textures under the variation of the field tilt angle correlates with the appearance of an incompressible state at ν = 3/2.