Effect of exchange-type zero-bias anomaly on single-electron tunneling of Au nanoparticles

Using cryogenic scanning tunneling microscopy and scanning tunneling spectroscopy, single-electron tunneling of Au nanoparticles (NPs) with 1.4 nm in radius was studied. We observe a gap Delta V similar to 2e/C (C is the capacitance of the Au particle and e the charge of an electron) around zero bias in the tunneling-conductance spectrum, followed by a series of discrete single-electron tunneling peaks with peak spacing of E(C) similar to e/C at both negative and positive bias. Experimental data are well explained by taking into account both the shift of conductance peaks and the effect of exchange interaction of electrons on the single-electron tunneling of Au NPs. A conductance peak near zero bias was suppressed by the exchange-type zero-bias anomaly, which results in the gap Delta V similar to 2E(C). According to our experiment and analysis, the shift of conductance peaks of Au NPs is attributed to self-biased gate and/or tip-induced gate.