Quantum Hall spin textures far beyond the skyrmion limit

Physical Review B: Condensed Matter and Materials Physics. 2022. Vol. 106. No. 24. Article 245308.

A. B. Van'kov, Koreyev A. S., P. S. Berezhnoy, I. V. Kukushkin

In strongly correlated quantum Hall ferromagnets with noninteger filling factors between ν = 1 and ν =
3/2, evidence of offbeat spin textures is obtained. The platforms for the study are two-dimensional electron
systems based on MgZnO/ZnO heterostructures, in which the parameters of Zeeman and exchange energies are
inconsistent with ordinary skyrmions. Experimental probing of magnetic order is fulfilled via exploration of
the spectra of collective spin excitations by means of inelastic light scattering. In addition to the ferromagnetic
spin exciton, a low-energy spin mode is observed, bearing witness to broken spin-rotational symmetry in the
ground state. The two spin modes exhibit a pronounced anticrossing behavior, depending on the two-dimensional
momentum, electron concentration, filling factor, and magnetic field tilt. The properties of the electron system
are simulated using the exact diagonalization technique, showing that Landau level mixing and crossing play
a key role in the nontrivial spin configuration. The corresponding spin textures emerging between ν = 1 and
ν = 3/2 involve the orbital degree of freedom and are qualitatively different from skyrmions. Experiments at
elevated temperatures show the destruction of this orbital spin texture phase with critical temperature far below
the Zeeman energy. On the other side of ν = 1 the textures are absent.

Keywords: Two-dimensional electron system, квантовый эффект Холла, quantum Hall effect, collective excitations, коллективные возбуждения, inelastic light scattering, неупругое рассеяние света, Двумерные электронные системы, spin textures, спиновые текстуры