Spin and the Coulomb Gap in the Half-Filled Lowest Landau Level

TL;DR

This paper investigates how an in-plane magnetic field influences the Coulomb gap in tunneling between two 2D electron systems at half filling, revealing a link to spin polarization transitions.

Contribution

It demonstrates the dependence of the Coulomb gap on in-plane magnetic fields and connects this behavior to the spin polarization state of the system.

Findings

Coulomb gap width increases sharply with in-plane field at low density.

Abrupt leveling off of gap width correlates with spin polarization transition.

Tunneling gap provides insights into spin configurations at high magnetic fields.

Abstract

The Coulomb gap observed in tunneling between parallel two-dimensional electron systems, each at half filling of the lowest Landau level, is found to depend sensitively on the presence of an in-plane magnetic field. Especially at low electron density, the width of the Coulomb gap at first increases sharply with in-plane field, but then abruptly levels off. This behavior appears to coincide with the known transition from partial to complete spin polarization of the half-filled lowest Landau level. The tunneling gap therefore opens a new window onto the spin configuration of two-dimensional electron systems at high magnetic field.