Anomalous giant piezoresistance in AlAs 2D electrons with anti-dot lattices

TL;DR

This paper reports a giant, anomalous piezoresistance effect in AlAs 2D electron systems patterned with anti-dot lattices, caused by non-uniform strain and valley-dependent electron exclusion, resembling giant magnetoresistance.

Contribution

It introduces a novel giant piezoresistance phenomenon in patterned AlAs 2D electrons, linking strain and valley physics to a GMR-like effect.

Findings

Observation of sign-opposite GPR in patterned vs. unpatterned regions

Attribution of GPR to non-uniform strain and valley exclusion

Analogy between GPR and GMR effects

Abstract

An AlAs two-dimensional electron system patterned with an anti-dot lattice exhibits a giant piezoresistance (GPR) effect, with a sign opposite to the piezoresistance observed in the unpatterned region. We trace the origin of this anomalous GPR to the non-uniform strain in the anti-dot lattice and the exclusion of electrons occupying the two conduction band valleys from different regions of the sample. This is analogous to the well-known giant magnetoresistance (GMR) effect, with valley playing the role of spin and strain the role of magnetic field.