Pauli spin blockade in cotunneling transport through a double quantum   dot
  We study spin correlation in a double quantum dot containing a few electrons in each dot (around 10). Clear current rectification with negative differential conductance is observed in the cotunneling regime, which is well explained by a Pauli spin blockade. The current feature is discussed in connection with exchange singlet-triplet splitting based on two simple models, one of which takes coherent interdot coupling and the other incoherent interdot coupling into account. 
H. W. Liu, T. Fujisawa, T. Hayashi and Y. Hirayama