Valley blockade and multielectron spin-valley Kondo effect in silicon

TL;DR

This paper investigates the valley blockade and multielectron spin-valley Kondo effect in silicon nano devices, revealing how electron filling influences Kondo phenomena and demonstrating valley index conservation without magnetic fields.

Contribution

It uncovers the periodicity of the Kondo effect related to silicon's electron filling and shows valley index conservation in SU(4) Kondo without external magnetic fields.

Findings

Kondo effect exhibits a periodicity of 4 with electron filling N=1, 2, 3.

Valley index conservation in SU(4) Kondo demonstrated without magnetic field.

Microwave irradiation suppresses the Kondo effect up to three electrons.

Abstract

We report on the valley blockade and the multielectron Kondo effect generated by an impurity atom in a silicon nano field effect device. According to the spin-valley nature of tunnelling processes, and consistently with those allowed by the valley blockade regime, the manifestation of Kondo effect obeys to the periodicity 4 of the electron filling sequence typical of silicon emerging at occupation N=1, 2, 3. The spin-valley Kondo effect emerges under different kinds of screening depending on the electron filling. By exploiting the valley blockade regime, valley index conservation in the Kondo SU(4) is deduced without the employment of an external magnetic field. Microwave irradiation suppresses the Kondo effect at occupancies up to three electrons.