Magnetic phenomena at and near nu = 1 / 2 and 1 / 4: theory, experiment, and interpretation

I show that the Hamiltonian theory of composite fermions is capable of yielding a unified description in fair agreement with recent experiments on polarization P and relaxation rate 1/T1 in quantum Hall states at filling nu = p/(2ps+1), at and near nu = 1 / 2 and 1 / 4 ( s = 1,2) at zero and nonzero temperatures. I show how rotational invariance and two dimensionality can make the underlying interacting theory behave like a free one in a limited context.