Reorientation of the stripe Phase of 2D Electrons by a Minute Density Modulation

TL;DR

This study demonstrates that a very small periodic density modulation can reorient the stripe phase of 2D electrons in a quantum well, competing with magnetic field effects.

Contribution

It reveals that minute density modulations can control the orientation of stripe phases, a novel method for manipulating electronic nematic order.

Findings

A surface strain grating induces a density modulation less than 0.25%.

Such a small modulation can reorient the stripe phase.

The stripe orientation aligns with the surface grating despite magnetic field influence.

Abstract

Interacting two-dimensional electrons confined in a GaAs quantum well exhibit isotropic transport when the Fermi level resides in the first excited ($N=1$) Landau level. Adding an in-plane magnetic field ($B_{||}$) typically leads to an anisotropic, stripe-like (nematic) phase of electrons with the stripes oriented perpendicular to the $B_{||}$ direction. Our experimental data reveal how a periodic density modulation, induced by a surface strain grating from strips of negative electron-beam resist, competes against the $B_{||}$-induced orientational order of the stripe phase. Even a minute ($<0.25\%$) density modulation is sufficient to reorient the stripes along the direction of the surface grating.