Combined effect of electron-electron interactions and spin-orbit scattering in metal nanoparticles

The combined effect of electron-electron interactions and spin-orbit scattering in metal nanoparticles can be studied by measuring splitting of electron levels in magnetic field (g factors) in tunneling spectroscopy experiments. Using random matrix theory to describe the single-electron states in the metal particle, we find that even a relatively small electron-electron interaction strength (ratio of exchange constant J and mean level spacing δ≃0.3) significantly increases g-factor fluctuations for not-too-strong spin-orbit scattering rates (spin-orbit time τ S O ≥ 1/δ). In particular, g factors larger than 2 could be observed. (This is a manifestation of the many-body correlation effects in nanoparticles). While so far measurements only on noble metal (Cu, Ag, Au) and Al samples have been done for which the effects of electron-electron interactions are negligible, we discuss the possibility of observing interaction effects in nanoparticles made of other metals.