Status of the Fermi surface in mixed composite boson - composite fermion quantum Hall states

TL;DR

This paper analyzes the Fermi surface in mixed composite boson-fermion quantum Hall states, concluding that expected singularities are absent and suggesting a novel phenomenon where Fermi-liquid regions expand in volume without symmetry breaking.

Contribution

It provides a detailed analysis of the Fermi surface in mixed quantum Hall states, revealing the obliteration of expected singularities and proposing a new phenomenon related to Fermi-liquid volume expansion.

Findings

Singularities of the Fermi surface are obliterated in mixed states.

A potential new phenomenon where Fermi-liquid volume enlarges without symmetry breaking.

Analysis based on momentum distribution in single-layer composite-fermion states.

Abstract

We argue that the naively expected singularities of the Fermi surface, in the mixed composite boson - composite fermion states proposed [S.H. Simon et al., PRL 91, 046803(2003)] for the evolution of \nu = 1 bilayer quantum Hall system with distance, are obliterated. Our conclusion is based on a careful analysis of the momentum distribution in \nu = 1/2 single-layer composite-fermion state. We point out to a possibility of the phenomenon hitherto unknown outside Kondo lattice systems when, in a translationally invariant system, Fermi-liquid-like portion of electrons enlarges its volume.