Magnetic-Field-Induced Crossover to a Nonuniversal Regime in a Kondo Dot

Abstract

We have measured the magnetic splitting, ${\Delta }_K$, of a Kondo peak in the differential conductance of a Single-Electron Transistor while tuning the Kondo temperature, $T_K$, along two different paths in the parameter space: varying the dot-lead coupling at a constant dot energy, and vice versa. At a high magnetic field, $B$, the changes of ${\Delta }_K$ with $T_K$ along the two paths have opposite signs, indicating that ${\Delta }_K$ is not a universal function of $T_K$. At low $B$, we observe a decrease in ${\Delta }_K$ with $T_K$ along both paths, in agreement with theoretical predictions. Furthermore, we find ${\Delta }_K/\Delta <1$ at low $B$ and ${\Delta }_K/\Delta >1$ at high $B$, where $\Delta$ is the Zeeman energy of the bare spin, in the same system.

12 pages, 5 figures

References in corpus (1)

• Nonequilibrium Transport through a Kondo Dot in a Magnetic Field: Perturbation Theory