Inelastic light scattering spectroscopy around the \nu=1/3 filling discloses a novel type of cyclotron spin-flip excitation in a quantum Hall system in addition to the excitations previously studied. The excitation energy of the observed mode follows qualitatively the degree of electron spin polarization, reaching a maximum value at \nu=1/3 and thus characterizing it as a \nu=1/3 ferromagnet eigenmode. Its absolute energy substantially exceeds the theoretical prediction obtained within the renowned single-mode approximation. Double-exciton corrections neglected utilizing the single-mode approach are evaluated within the framework of the excitonic representation and are inferred to be responsible for the observed effect.
@article{arxiv.0812.4890,
title = {Cyclotron spin-flip excitations in a \nu=1/3 quantum Hall ferromagnet},
author = {A. B. Van'kov and L. V. Kulik and S. M. Dickmann and I. V. Kukushkin and V. E. Kirpichev and W. Dietsche and S. Schmult},
journal= {arXiv preprint arXiv:0812.4890},
year = {2010}
}