Phase diagram of the integer quantum Hall effect in p-type Germanium

TL;DR

This study maps the phase diagram of the integer quantum Hall effect in p-type Germanium, revealing unique level behaviors and transition patterns influenced by the material's properties and magnetic field variations.

Contribution

It provides the first detailed experimental phase diagram of the integer quantum Hall effect in p-type Ge, highlighting the absence of floating of higher levels and the merging of levels into the insulator.

Findings

Lowest energy level floats up at low fields near the transition

Higher energy levels merge into the insulating state without floating

Critical resistivity peaks around filling factor one

Abstract

We experimentally study the phase diagram of the integer quantized Hall effect, as a function of density and magnetic field. We used a two dimensional hole system confined in a Ge/SiGe quantum well, where all energy levels are resolved, because the Zeeman splitting is comparable to the cyclotron energy. At low fields and close to the quantum Hall liquid-to-insulator transition, we observe the floating up of the lowest energy level, but NO FLOATING of any higher levels, rather a merging of these levels into the insulating state. For a given filling factor, only direct transitions between the insulating phase and higher quantum Hall liquids are observed as a function of density. Finally, we observe a peak in the critical resistivity around filling factor one.