Two-stage Kondo effect in single Manganese phthalocyanine molecule transistor

Charge and spin manipulation over single molecule is important for understanding various fundamental physical processes down to molecular level. In single molecule device, when the coupling between molecule and electrodes is enhanced, localize electron spin strongly interacts with electrons in the electrodes, forming Kondo effect. In this talk, I will discuss our efforts on manipulation of Kondo effect in single Manganese Phthalocyanine (MnPc) device. We use electromigration method fabricating single MnPc molecule field effect transistor successfully. Two stage Kondo and S=1/2 Kondo resonance were observed in different charge states. Two-stage Kondo effect was examed against temperature and electric field. Evolution of Kondo temperatures of the two stages in the field will be discussed. We also observed magnet field induced quantum phase transition between spin singlet and spin triplet in this system. These results illustrate spin control in multi electrons system at single molecule scale.