Missing 2k_F Response for Composite Fermions in Phonon Drag

TL;DR

This study investigates the response of composite Fermions to large wavevector scattering via phonon drag, revealing discrepancies from theoretical expectations, especially in temperature dependence, challenging current models.

Contribution

It provides new experimental insights into composite Fermion responses, highlighting deviations from existing theories at large wavevectors and varying densities.

Findings

Discrepancies in response at large wavevectors compared to theory

Deviations in temperature dependence for 2k_F scattering

Differences observed when changing density versus magnetic field

Abstract

The response of composite Fermions to large wavevector scattering has been studied through phonon drag measurements. While the response retains qualitative features of the electron system at zero magnetic field, notable discrepancies develop as the system is varied from a half-filled Landau level by changing density or field. These deviations, which appear to be inconsistent with the current picture of composite Fermions, are absent if half-filling is maintained while changing density. There remains, however, a clear deviation from the temperature dependence anticipated for 2k_F scattering.