Activated transport in the v = 1 bilayer quantum Hall states with small tunneling energy Δ_SAS = 1K

We carried out magnetotransport experiments in the v = 1 bilayer quantum Hall state (BQHS) using a GaAs/AlAs double-quantum-well structure with tunneling energy as small as 1 K. We focus on measurements of not only activation energies but also onset temperatures of the BQHS for a wide range of the total density and the layer density imbalance. We have found that the dependency of onset temperature on the total density is different from that of the activation energy. We discuss physical interpretations of the onset temperature with relationship to finite-temperature phase transitions in the v = 1 BQHS.