Neutral Fermions at $\nu=1/2$

TL;DR

This paper develops a particle-hole symmetric theory for a 2D electron gas at half-filling, describing dipole-like fermions that can form a Fermi-liquid or a quantum critical state under disorder.

Contribution

It introduces a novel particle-hole symmetric framework with dipole-like fermions for the $ u=1/2$ quantum Hall system, highlighting the effects of disorder.

Findings

Dipole-like fermions can form a Fermi-liquid in clean systems.

Disorder can break dipoles, leading to a quantum critical state.

The theory maintains particle-hole symmetry at $ u=1/2$.

Abstract

We present a particle-hole symmetric theory for a two-dimensional electron gas at filling factor one half. In this theory, elementary excitations are dipole-like fermions floating on top of the $\nu=1/2$ boson quantum Hall liquid. In the absence of disorder these dipoles can form a Fermi-liquid. Disorder can break them apart and drive the ground state into a quantum critical state.