Spin-Valley Kondo Effect in Multi-electron Silicon Quantum Dots

Abstract

We study the spin-valley Kondo effect of a silicon quantum dot occupied by electrons, with $\mathcal{N}$ up to four. We show that the Kondo resonance appears in the $\mathcal{N}=1,2,3$ Coulomb blockade regimes, but not in the $\mathcal{N}=4$ one, in contrast to the spin-1/2 Kondo effect, which only occurs at $\mathcal{N}=$ odd. Assuming large orbital level spacings, the energy states of the dot can be simply characterized by fourfold spin-valley degrees of freedom. The density of states (DOS) is obtained as a function of temperature and applied magnetic field using a finite-U equation-of-motion approach. The structure in the DOS can be detected in transport experiments. The Kondo resonance is split by the Zeeman splitting and valley splitting for double- and triple-electron Si dots, in a similar fashion to single-electron ones. The peak structure and splitting patterns are much richer for the spin-valley Kondo effect than for the pure spin Kondo effect.

8 pages, 4 figures, in PRB format. This paper is a sequel to the paper published in Phys. Rev. B 75, 195345 (2007)

References in corpus (6)

• Controllable valley splitting in silicon quantum devices
• On the applicability of the equations-of-motion technique for quantum dots
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• Coulomb blockade and Kondo effect in a few-electron silicon/silicon-germanium quantum dot
• Conductance of a spin-1 quantum dot: the two-stage Kondo effect
• Valley Kondo Effect in Silicon Quantum Dots

Cited by in corpus (6)

• Silicon Quantum Electronics
• Kondo effect in carbon nanotube quantum dots with spin-orbit coupling
• Valley blockade and multielectron spin-valley Kondo effect in silicon
• Signatures of Valley Kondo Effect in Si/SiGe Quantum Dots
• Diffusion Monte Carlo study of a valley degenerate electron gas and application to quantum dots
• Fractional shot noise of an SU(N) Kondo system