Skyrmions in a Half-Filled Second Landau Level

We studied charged excitations of the ?=5/2 fractional quantum Hall state allowing for spin depolarization. It is generally accepted that the ground state is a spin?polarized incompressible quantum liquid, adiabatically connected to the Pfaffian state, whose spin?polarized quasiholes (QHs) obey non?Abelian statistics. Using numerical diagonalization and taking account of non?zero well widths we demonstrated that at a sufficiently low Zeeman energy it is energetically favorable for pairs of charge e/4 QHs to bind into charge e/2 Skyrmions. We showed that Skyrmion formation is further promoted by disorder, and argue that this can lead to a depolarized ground state in realistic experimental situations.