Theories for v=1/2 in Single- and Double-Layer Systems

TL;DR

This paper discusses theoretical models explaining the occurrence of quantum Hall effects at v=1/2 in single and double-layer systems, highlighting differences and proposing a fermion Chern-Simons framework.

Contribution

It extends the fermion Chern-Simons theory to double-layer systems at v=1/2, providing a unified theoretical approach for both single and double-layer quantum Hall states.

Findings

Quantized Hall plateau observed in double-layer systems at v=1/2.

Single-layer systems lack a plateau at v=1/2, explained by different ground state theories.

Fermion Chern-Simons theory offers insights into the ground states of both systems.

Abstract

Recent experiments have shown that a quantized Hall plateau can occur in double layer systems at total filling factor v=1/2, though there is no plateau at v=1/2 in a normal single layer system. For the single layer system, considerable insight has been provided by a theory based on the fermion Chern-Simons picture, where the electrons are transformed into fermions that carry two flux quanta of a Chern-Simons gauge field. A similar picture can be used to characterize ground states which have been proposed for the two layer system.