Contrasting Behavior of the 5/2 and 7/3 Fractional Quantum Hall Effect in a Tilted Field

TL;DR

This study investigates how tilted magnetic fields differently affect the 5/2 and 7/3 fractional quantum Hall states, revealing contrasting behaviors linked to Zeeman and orbital effects, with implications for understanding their underlying wavefunctions.

Contribution

It provides new experimental insights into the distinct responses of the 5/2 and 7/3 states to in-plane magnetic fields, highlighting the role of Zeeman and orbital couplings.

Findings

The 5/2 state gap collapses linearly with in-plane field above ~0.5 T.

The 7/3 state gap is strongly enhanced by the in-plane field.

Distinct behaviors are explained by Zeeman and magneto-orbital interactions.

Abstract

Using a tilted field geometry, the effect of an in-plane magnetic field on the even denominator nu = 5/2 fractional quantum Hall state is studied. The energy gap of the nu = 5/2 state is found to collapse linearly with the in-plane magnetic field above ~0.5 T. In contrast, a strong enhancement of the gap is observed for the nu = 7/3 state. The radically distinct tilted-field behaviour between the two states is discussed in terms of Zeeman and magneto-orbital coupling within the context of the proposed Moore-Read pfaffian wavefunction for the 5/2 fractional quantum Hall effect.