University of Oxford

Title: Spin textures, screening and excitations in dirty quantum Hall ferromagnets

Abstract: We study quantum Hall ferromagnets in the presence of a random electrostatic impurity potential. Describing these systems with a classical non-linear sigma model and using analytical estimates supported by results from numerical simulations, we examine the nature of the ground state as a function of disorder strength, D, and deviation, dn, of the average Landau level filling factor from unity. Screening of an impurity potential requires distortions of the spin configuration, and in the absence of Zeeman coupling there is a disorder-driven, zero-temperature phase transition from a ferromagnet at small D and |dn| to a spin glass at larger D or |dn|. We examine ground-state response functions and excitations.