Anomalous Kondo-effect in Quantum Dot at non-zero bias

TL;DR

This paper reports on the observation of an anomalous Kondo-effect in a quantum dot under non-zero bias, showing asymmetric resonance behavior and exploring spin blockade effects to understand the dot's spin state.

Contribution

The study demonstrates the pinning of the Kondo resonance to lead Fermi levels and introduces a method to probe the quantum dot's spin state via spin blockade.

Findings

Kondo resonance is offset at zero magnetic field.

Resonance persists in negative bias but is suppressed in positive bias.

Spin blockade provides information about the dot's spin state.

Abstract

We present measurements on the Kondo-effect in a small quantum dot connected strongly to one lead and weakly to the other. The conductance of the dot reveals an offset of the Kondo resonance at zero magnetic field. While the resonance persists in the negative bias regime, it is suppressed in the opposite direction. This demonstrates the pinning of the Kondo resonance to the Fermi levels of the left and right lead. As an outlook we exploit the spin blockade effect to gain information about the spin state of the quantum dot in the Kondo regime.