Inter-Landau-level skyrmions versus quasielectrons in the v=2 quantum Halleffects

We consider the charged excitations in the quantum Hall effect with a large Zeeman splitting at filling factor v=2, When the Zeeman splitting is incre ased over a critical value the ground state undergoes a first order phase t ransition from a paramagnetic to a ferromagnetic phase. We have studied the possibility of forming charged spin-textured excitations, "inter-Landau-le vel skyrmions," close to this transition; and find that these are never 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 v = 2 phase transition ans of the olarization at higher filling factors are also presented.