Spontaneous Interlayer Coherence in Double-Layer Quantum Hall Systems: Symmetry Breaking Interactions, In-Plane Fields and Phase Solitons

TL;DR

This paper investigates how weak interlayer tunneling and in-plane magnetic fields influence the phase coherence, excitations, and phase transitions in double-layer quantum Hall systems with spontaneous interlayer coherence.

Contribution

It analyzes the effects of tunneling and magnetic fields on symmetry breaking, response functions, and excitations in double-layer quantum Hall systems, providing new insights into their phase behavior.

Findings

Weak tunneling modifies interlayer coherence properties.

Parallel fields induce a transition to an incommensurate state.

Response functions reveal analogies with Josephson junctions.

Abstract

At strong magnetic fields double-layer two-dimensional-electron-gas systems can form an unusual broken symmetry state with spontaneous inter-layer phase coherence. The system can be mapped to an equivalent system of pseudospin $1/2$ particles with pseudospin-dependent interactions and easy-plane magnetic order. In this paper we discuss how the presence of a weak interlayer tunneling term alters the properties of double-layer systems when the broken symmetry is present. We use the energy functional and equations of motion derived earlier to evaluate the zero-temperature response functions of the double-layer system and use our results to discuss analogies between this system and Josephson-coupled superconducting films. We also present a qualitative picture of the low-energy charged excitations of this system. We show that parallel fields induce a highly collective phase transition to an incommensurate state with broken translational symmetry.