| speaker: |
David Goldhaber-Gordon Stanford, USA |
| time: | Fr., 17.08, 11:00 - 12:00 |
This talk will discuss how perturbations (temperature, bias, magnetic field) modify the Kondo effect, as expressed in measurements of transport through a quantum dot. First, how do temperature and bias affect transport through a Kondo quantum dot? I will show that low energy conductance exhibits scaling as a function of bias and temperature. Transport is well described by a two parameter universal function. The extracted parameters agree well with NRG calculations which take into account the fact that a dot equally coupled to two leads with a bias between them is not in equilibrium with a single reservoir. Second, how does the density of states of a Kondo dot evolve with magnetic field? The splitting of spin-resolved Kondo resonances at low magnetic field, and how it crosses over to a simple, well-understood behavior at high fields, has been a subject of much investigation over the past 15 years. In measurements on a quantum dot in a carbon nanotube, we extract a splitting of peaks in density of states proportional to magnetic field at high fields, contrary to recent reports. At lower fields, the splitting falls below this linear dependence, in qualitative but not quantitative agreement with theoretical expectations.