Physics Department News

We study many-body interaction effects in the spatially resolved filling factor distribution for higher Landau levels (LLs) via self-consistent Hartree-Fock simulations in the integer quantum Hall (IQH) regime. Our results indicate a strong, interaction-induced tendency to avoid the simultaneous existence of partially filled spin-up and spin-down LLs. Rather, we find that such partially filled LLs consist of coexisting regions of full and empty LLs. At the boundaries between the regions of full and empty LLs, we observe edge stripes of nearly constant filling close to half-odd filling. This suggests that the exchange interaction induces a behavior similar to a Hund’s rule for the occupation of the spin split LLs. The screening of the disorder and edge potential appears significantly reduced as compared to static Thomas-Fermi screening. Our results are consistent with a local, lateral filling factor dependence of the exchange-enhanced spin splitting. Hence, on quantum-coherent length scales as probed here, the electron system of the IQH effect behaves similarly to a non-interacting single particle system - not because of the absence, but rather due to the dominance of many-body effects. The work has now been published as EPL, 117 (2017) 57009, doi: 10.1209/0295-5075/117/57009.