Abstract
We report sharp peaks in the differential conductance of a single-electron transistor (SET) at low temperature for gate voltages at which charge fluctuations are suppressed. For odd numbers of electrons we observe the expected Kondo peak at zero bias. For even numbers of electrons we generally observe Kondo-like features corresponding to excited states. For the latter, the excitation energy often decreases with gate voltage until a new zero-bias Kondo peak results. We ascribe this behavior to a singlet-triplet transition in zero magnetic field driven by the change of shape of the potential that confines the electrons in the SET.
- Received 5 December 2002
DOI:https://doi.org/10.1103/PhysRevB.67.113309
©2003 American Physical Society