Internal Excitations and Dissipative Damping of Quantum Hall Skyrmions

We propose an intrinsic maximum speed for dissipationless E cross B drift of Skyrmion quasiparticles in quantum Hall ferromagnets. When this speed is exceeded, Skyrmions can radiate spin-waves by making internal excitations which allow total spin to be conserved. Our proposal is illustrated by a time-dependent Hartree-Fock approximation calculation of the excitation spectrum for a Skyrmion bound to an impurity.