Multiple interacting bilayer electron system: Magnetotransport and heat capacity measurements.

We report the fabrication, magnetotransport, and heat capacity measurements on a GaAs/AlGaAs multiple double-quantum-well heterostructure in the quantum Hall (QH) regime. Magnetotransport data reveal the existence of a correlated QH state at total Landau level filling factor nu(t) = 1. Near nu(t) = 2, we observe the nuclear contribution to the measured heat capacity of the Ga and As atoms in GaAs quantum wells. The heat capacity data indicate that Skyrmions are the lowest-energy excitations of the nu(t) = 2 ferromagnetic QH ground state.