Ettingshausen Effect around Landau Level Filling Factor nu=3 Studied by Dynamic Nuclear Polarization

TL;DR

This study investigates the Ettingshausen effect and spin current behavior near Landau level filling factor nu=3 in a GaAs/AlGaAs 2D electron system, revealing a reversal in spin current polarity associated with Landau level filling changes.

Contribution

It provides new insights into the spin current dynamics and nuclear polarization around nu=3, highlighting the reversal of spin current polarity at this filling factor.

Findings

Spin current reverses polarity at nu=3.

Dynamic nuclear polarization indicates spin current direction change.

Reversal linked to Landau level filling transition.

Abstract

Spin current perpendicular to the electric current is investigated around Landau level filling factor $\nu=3$ in a GaAs/AlGaAs two-dimensional electron system. Measurements of dynamic nuclear polarization in the vicinity of the edge of a specially designed Hall bar sample indicate that the direction of the spin current with respect to the Hall electric field reverses its polarity at $\nu=3$, where the dissipative current carried by holes in the spin up Landau level is replaced with that by electrons in the spin down Landau level.