The electromagnetic characteristics of bilayer quantum Hall systems in thepresence of interlayer coherence and tunneling are studied by means of apseudospin-texture effective theory and an algebraic framework of thesingle-mode approximation, with emphasis on clarifying the nature of thelow-lying neutral collective mode responsible for interlayer tunnelingphenomena. A long-wavelength effective theory, consisting of the collectivemode as well as the cyclotron modes, is constructed. It is seen explicitly fromthe electromagnetic response that gauge invariance is kept exact, thisimplying, in particular, the absence of the Meissner effect in bilayer systems.Special emphasis is placed on exploring the advantage of looking into quantumHall systems through their response; in particular, subtleties inherent to thestandard Chern-Simons theories are critically examined.
展开▼
