Dissipationless transport in low density bilayer systems

TL;DR

This paper discusses the theoretical prediction and experimental signatures of dissipationless, superfluid-like transport in low-density bilayer electronic systems, both at zero magnetic field and in quantum Hall regimes.

Contribution

It introduces the concept of an XY isospin-ordered ferromagnetic phase in bilayer systems at zero magnetic field, extending the understanding of superfluidity in these materials.

Findings

Superfluidity persists at zero magnetic field despite being gapless.

Weak disorder does not destroy superfluidity in these systems.

Experimental signatures include Coulomb drag and collective mode measurements.

Abstract

In a bilayer electronic system the layer index may be viewed as the z-component of an isospin-1/2. An XY isospin-ordered ferromagnetic phase was observed in quantum Hall systems and is predicted to exist at zero magnetic field at low density. This phase is a superfluid for opposite currents in the two layers. At B=0 the system is gapless but superfluidity is not destroyed by weak disorder. In the quantum Hall case, weak disorder generates a random gauge field which probably does not destroy superfluidity. Experimental signatures include Coulomb drag and collective mode measurements.