Inter-Landau-level skyrmions versus quasielectrons in the nu=2 quantum Hall effect

Abstract

We consider the charged excitations in the quantum Hall effect with a large Zeeman splitting at filling factor nu=2. When the Zeeman splitting is increased over a critical value the groundstate undergoes a first order phase transition from a paramagnetic to a ferromagnetic phase. We have studied the possibility to form charged spin-textured excitations, "inter Landau level Skyrmions", close to this transition and find that these never are the lowest lying charged excitations but can under certain conditions provide an effective driving mechanism for the paramagnetic to ferromagnetic phase transition. We show that the charged excitations inevitably present in the system can act as nucleation centers even at T=0 and hence set a specific limit for the maximal hysteresis attainable in this case. Calculations of how the finite width of the two-dimensional electron gas affects the nu=2 phase transition and the polarization at higher filling factors are also presented.