Bilayer quantum Hall system atνt=1: Pseudospin models and in-plane magnetic field

摘要

We investigate two theoretical pseudomagnon-based models for a bilayerquantum Hall system (BQHS) at total filling factor $u_t = 1$. We find aunifying framework which elucidates the different approximations that are made.We also consider the effect of an in-plane magnetic field in BQHSs at $u_t =1$, by deriving an equation for the ground state energy from the underlyingmicroscopic physics. Although this equation is derived for small in-planefields, its predictions agree with recent experimental findings at strongerin-plane fields, for low electron densities. We also take into accountfinite-temperature effects by means of a renormalisation group analysis, andfind that they are small at the temperatures that were investigatedexperimentally.