Observation of the Kondo Effect in a Spin-3/2 Hole Quantum Dot

TL;DR

This paper reports the experimental observation of Kondo physics in a spin-3/2 hole quantum dot, highlighting unique Zeeman splitting behavior and strong spin-orbit interaction effects in a GaAs heterostructure.

Contribution

First observation of Kondo effect in a spin-3/2 hole quantum dot with detailed analysis of Zeeman splitting and spin-orbit interaction effects.

Findings

Zeeman spin-splitting of zero-bias peak is gate-voltage independent

Splitting is twice as large as in lowest 1D subband

Splitting is highly anisotropic due to spin-orbit interaction

Abstract

We report the observation of Kondo physics in a spin- 3/2 hole quantum dot. The dot is formed close to pinch-off in a hole quantum wire defined in an undoped AlGaAs/GaAs heterostructure. We clearly observe two distinctive hallmarks of quantum dot Kondo physics. First, the Zeeman spin-splitting of the zero-bias peak in the differential conductance is independent of gate voltage. Second, this splitting is twice as large as the splitting for the lowest one-dimensional subband. We show that the Zeeman splitting of the zero-bias peak is highly-anisotropic, and attribute this to the strong spin-orbit interaction for holes in GaAs.