Signatures of Valley Kondo Effect in Si/SiGe Quantum Dots

TL;DR

This paper presents experimental evidence of the valley Kondo effect in Si/SiGe quantum dots, highlighting unique conductance features influenced by valley and Zeeman splittings, with implications for quantum dot spintronics.

Contribution

It provides the first detailed experimental observation of the valley Kondo effect in silicon-based quantum dots, including the influence of valley and magnetic field interactions.

Findings

Observation of conductance peaks with strong temperature dependence.

Unusual behavior of Kondo peaks in magnetic fields due to valley effects.

Detection of zero-bias conductance peaks indicating valley non-conservation.

Abstract

We report measurements consistent with the valley Kondo effect in Si/SiGe quantum dots, evidenced by peaks in the conductance versus source-drain voltage that show strong temperature dependence. The Kondo peaks show unusual behavior in a magnetic field that we interpret as arising from the valley degree of freedom. The interplay of valley and Zeeman splittings is suggested by the presence of side peaks, revealing a zero-field valley splitting between 0.28 to 0.34 meV. A zero-bias conductance peak for non-zero magnetic field, a phenomenon consistent with valley non- conservation in tunneling, is observed in two samples.