Probing quantum phases in ultra-high-mobility two-dimensional electron systems using surface acoustic waves

TL;DR

This study uses low-power surface acoustic waves to probe quantum phases in ultra-high-mobility 2D electron systems, revealing that quantum phases become more incompressible under minimal perturbation, challenging traditional transport measurement assumptions.

Contribution

It introduces a novel low-power acoustic probing method to study quantum phases, minimizing perturbation compared to conventional transport techniques.

Findings

Quantum phases become more incompressible with perturbative current.

Surface acoustic waves can effectively probe electron system properties.

Lower power acoustic measurements reveal new insights into quantum phase behavior.

Abstract

Transport measurement, which applies an electric field and studies the migration of charged particles, i.e. the current, is the most widely used technique in condensed matter studies. It is generally assumed that the quantum phase remains unchanged when it hosts a sufficiently small probing current, which is, surprisingly, rarely examined experimentally. In this work, we study the ultra-high mobility two-dimensional electron system using a propagating surface acoustic wave, whose traveling speed is affected by the electrons' compressibility. The acoustic power used in our study is several orders of magnitude lower than previous reports, and its induced perturbation to the system is smaller than the transport current. Therefore we are able to observe the quantum phases become more incompressible when hosting a perturbative current.