Optical Probing of the Spin Polarization of the nu=5/2 Quantum Hall State

TL;DR

This study uses polarization-resolved photoluminescence spectroscopy to investigate the spin polarization of the nu=5/2 quantum Hall state, revealing it to be unpolarized based on energy splitting behavior.

Contribution

It provides the first direct optical measurement indicating the spin unpolarized nature of the nu=5/2 quantum Hall state, contrasting previous assumptions.

Findings

Sharp discontinuity in Landau level emission energy near nu=5/2

Splitting matches the bare Zeeman energy at nu=5/2

Behavior suggests the state is unpolarized

Abstract

We apply polarization resolved photoluminescence spectroscopy to measure the spin polarization of a two dimensional electron gas in perpendicular magnetic field. In the vicinity of filling factor nu=5/2, we observe a sharp discontinuity in the energy of the zero Landau level emission line. We find that the splitting between the two circular polarizations exhibits a sharp drop at nu=5/2 and is equal to the bare Zeeman energy, which resembles the behavior at even filling factors. We show that this behavior is consistent with filling factor nu=5/2 being unpolarized.