Temperature dependence of piezoresistance of composite Fermions with a valley degree of freedom

TL;DR

This study investigates how temperature and strain affect the transport properties of composite Fermions with valley degrees of freedom in AlAs quantum wells, revealing their metallic and insulating behaviors related to valley polarization.

Contribution

It provides the first detailed analysis of temperature dependence of piezoresistance in composite Fermions with valley degrees of freedom, highlighting their similarities to electrons.

Findings

Composite Fermions exhibit metallic behavior at low valley polarization.

Resistance becomes insulating as valley polarization increases.

Valley degrees of freedom significantly influence transport properties.

Abstract

We report transport measurements of composite Fermions at filling factor $\nu=3/2$ in AlAs quantum wells as a function of strain and temperature. In this system the composite Fermions possess a valley degree of freedom and show piezoresistance qualitatively very similar to electrons. The temperature dependence of the resistance (R) of composite Fermions shows a metallic behavior (dR/dT > 0) for small values of valley polarization but turns insulating (dR/dT < 0) as they are driven to full valley polarization. The results highlight the importance of discrete degrees of freedom in the transport properties of composite Fermions and the similarity between composite Fermions and electrons.