Order parameter suppression in double layer quantum Hall ferromagnets

TL;DR

This paper investigates how quantum fluctuations affect the spectral properties of double-layer quantum Hall ferromagnets at filling factor ν=1, revealing increased absorption near the phase boundary and linking spectral features to collective excitations.

Contribution

It provides a detailed analysis of quantum fluctuation effects on the spectral function and optical absorption in double-layer quantum Hall systems, highlighting the evolution near the phase transition.

Findings

Absorption strength increases as layer separation approaches the critical value.

Line shapes of absorption are related to collective excitation spectra.

Quantum fluctuations significantly influence spectral properties near the phase boundary.

Abstract

Double-layer quantum Hall systems at Landau level filling factor $\nu=1$ have a broken symmetry ground state with spontaneous interlayer phase coherence and a gap between symmetric and antisymmetric subbands in the absence of interlayer tunneling. We examine the influence of quantum fluctuations on the spectral function of the symmetric Green's function, probed in optical absorption experiments (cond-mat/9809373). We find that as the maximum layer separation at which the $\nu=1$ quantum Hall effect occurs is approached, absorption in the lowest Landau level grows in strength. Detailed line shapes for this absorption are evaluated and related to features in the system's collective excitation spectrum.