Excitation Spectrum of Composite Fermions

TL;DR

This paper investigates the excitation spectrum of composite fermions in fractional quantum Hall states, revealing differences from non-interacting electron spectra and discussing the nature of the compressible state at filling factor 1/2.

Contribution

It demonstrates that the excitation spectrum of composite fermions differs from that of non-interacting electrons, especially in collective modes, and provides insights into the compressible state at ν=1/2.

Findings

Composite fermion excitation spectrum differs from non-interacting electron spectrum.

Collective modes in fractional quantum Hall states are not analogous to integer states.

Speculation on the nature of the compressible state at ν=1/2.

Abstract

We show that the excitation spectrum of interacting electrons at filling factor $\nu=\nu^*/(2\nu^*+1)$ is well described in terms of non-interacting composite fermions at filling factor $\nu^*$, but does not have a one-to-one correspondence with the excitation spectrum of non-interacting electrons at $\nu^*$. In particular, the collective modes of the fractional quantum Hall states are not analogous to those of the integer quantum Hall states. We also speculate on the nature of the compressible state at $\nu=1/2$.