Electron Transport in Metallic Grains

Abstract

We discuss electron transport in individual nanometer-scale metallic grains at dilution refrigerator temperatures. In the weak coupling regime, the grains exhibit Coulomb blockade and discrete energy levels. Electron-electron interactions lead to clustering and broadening of quasiparticle states. Magnetic field dependences of tunneling resonances directly reveal Kramers degeneracy and Lande g-factors. In grains of Au, which have strong spin-orbit interaction, g-factors are strongly suppressed from the free electron value. We have recently studied grains in the strong coupling regime. Coulomb blockade persists in this regime. It leads to a suppression in sample conductance at zero bias voltage at low temperatures. The conductance fluctuates with the applied magnetic field near zero bias voltage. We present evidence that the fluctuations are induced by electron spin. This paper reviews the evolving progress in interpreting these observations.

Since the original submission, we have gathered data in weak coupling regime, showing that our initial speculation - that the conductance dip is due to EE interactions in the Altshuler-Aronov sense - is not correct. Instead, it is caused by the Coulomb Blockade. Conference Proceedings, "Quantum Transport and Quantum Coherence" Localisation 2002, Sophia University, Tokyo, August 16-19, to be published in the supplement of the Journal of the Physical Society of Japan

References in corpus (7)

• Spectroscopy of discrete energy levels in ultrasmall metallic grains
• Coulomb Interaction and Quantum Transport through a Coherent Scatterer
• Spectroscopy, Interactions and Level Splittings in Au Nanoparticles
• The g-factors of discrete levels in nanoparticles
• Studies of spin-orbit scattering in noble-metal nanoparticles using energy level tunneling spectroscopy
• Fluctuating spin g-tensor in small metal grains
• Effects of Spin-Orbit Interactions on Tunneling via Discrete Energy Levels in Metal Nanoparticles