10 research outputs found
Spin Reversal of a Quantum Hall Ferromagnet at a Landau Level Crossing
When Landau levels (LLs) become degenerate near the Fermi energy in the
quantum Hall regime, interaction effects can drastically modify the electronic
ground state. We study the quantum Hall ferromagnet formed in a two-dimensional
hole gas around the LL filling factor in the vicinity of a LL crossing
in the heave-hole valence band. Cavity spectroscopy in the strong-coupling
regime allows us to optically extract the two-dimensional hole gas' spin
polarization. By analyzing this polarization as a function of hole density and
magnetic field, we observe a spin flip of the ferromagnet. Furthermore, the
depolarization away from accelerates close to the LL crossing. This is
indicative of an increase in the size of Skyrmion excitations as the effective
Zeeman energy vanishes at the LL crossing