  At Landau level filling factors near nu =1, quantum Hall ferromagnets form a
Skyrme crystal state with quasi-long-range translational and non-collinear
magnetic order. We develop an effective low energy theory which explains the
presence in these systems of magnetic excitations at low energies below the
Larmor gap (Delta) and which predicts a dramatic enhancement of the nuclear
spin relaxation rate by a factor of 1000. The effective theory predicts a rich
set of quantum and classical phase transitions. Based in part on accurate
time-dependent Hartree-Fock calculations of the ordered state collective
excitation spectrum, we discuss aspects of the T-nu-Delta crystal phase
diagram.
