Phase Transition in \nu=2 Bilayer Quantum Hall State

TL;DR

This paper investigates phase transitions in bilayer quantum Hall states at different filling factors, revealing distinct stability behaviors and a phase transition at u=2 as electron density varies.

Contribution

It provides experimental evidence of a phase transition in the u=2 bilayer quantum Hall state linked to electron density changes.

Findings

u=1 state remains stable across all density differences.

u=2/3 state is stable only near balanced densities.

u=2 state exhibits a phase transition with changing electron density.

Abstract

The Hall-plateau width and the activation energy were measured in the bilayer quantum Hall state at filling factor \nu=2, 1 and 2/3, by changing the total electron density and the density ratio in the two quantum wells. Their behavior are remarkably different from one to another. The \nu=1 state is found stable over all measured range of the density difference, while the \nu=2/3$ state is stable only around the balanced point. The \nu=2 state, on the other hand, shows a phase transition between these two types of the states as the electron density is changed.