Excited States of Spins and Pseudospins in the ν = 2/3 Bilayer Quantum Hall Systems

We study excited states and excitation energies of the spins and pseudospins in different phases of the ν = 2/3 bilayer quantum Hall states using a GaAs/AlGaAs heterostructure sample. The phase boundaries are determined by the magnetoresistance measurements. The thermal activation energies at the perpendicular and titled magnetic fields reveal some characteristics of the spin and pseudospin skyrmion excitations in the special phases. We also use the theoretical models to fit the experimental data and obtain the effective numbers of the flipped spins or pseudospins per skyrmion.