In two-dimensional electron systems confined to wide AlAs quantum wells, composite fermions around the filling factor ν = 3/2 are fully spin polarized but possess a valley degree of freedom. Here we measure the energy needed to completely valley polarize these composite fermions as a function of electron density. Comparing our results to the existing theory, we find overall good quantitative agreement, but there is an unexpected trend: The measured composite fermion valley polarization energy, normalized to the Coulomb energy, decreases with decreasing density.
@article{arxiv.0907.0508,
title = {Density dependence of valley polarization energy for composite fermions},
author = {Medini Padmanabhan and T. Gokmen and M. Shayegan},
journal= {arXiv preprint arXiv:0907.0508},
year = {2009}
}