Magnetic-field-induced crossover to a nonuniversal regime in a Kondo dot.
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 parameter space: varying the dot-lead coupling at a constant dot energy and vice versa. At a high magnetic field B, the changes of DeltaK with TK along the two paths have opposite signs, indicating that Delta K is not a universal function of TK. At low B, we observe a decrease in DeltaK with TK 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.
Liu
Tai-Min
TM
Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221, USA.
Hemingway
Bryan
B
Kogan
Andrei
A
Herbert
Steven
S
Melloch
Michael
M