Doubly Enhanced Skyrmions in ν = 2 Bilayer Quantum Hall States

Abstract

Skyrmion excitations were measured and compared for the first time in the bilayer quantum Hall (QH) state at the Landau-level filling factor ν =2 and in the monolayer QH state at ν =1. The observed number of flipped spins, N_spin, is 14 in the bilayer sample with a large tunnelling gap, and N_spin=7 in the bilayer sample with a small tunnelling gap, while it is N_spin=7 in the monolayer sample. The difference is interpreted to be due to the interlayer exchange interaction.