Kondo-like effect in a strong spin-orbit interaction quantum point contact system
Chien-Wei Wu1*, Che-Wei Chang1, L. W. Smith2, I. Farrer2, D. A. Ritchie2, T.-M. Chen1
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
2Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, UK
* presenting author:Chien-Wei Wu, email:l26034166@mail.ncku.edu.tw
Kondo effect and spin-orbit interaction (SOI) are both fascinating problem in physics. Kondo effect can control the spin-flip due to the formation of singlet state between the unpaired localized electron and conducting electron. On the other hand, SOI realizes a complete control of electron spin in a purely electrical manner. Previous study [F. Kuemmeth et al., Nature 452, 448 (2008)], which observed the SOI and Kondo effect in carbon nanotube quantum dots, motivates us to investigate further physics in the interplay of SOI and Kondo effect.

Also, previous works had shown a number of similarities between QPC and Kondo effect in quantum dots [1,2]. Our device is based on QPC system and was fabricated on a InGaAs/InAs heterostructure for its tunable SOI strength. In such a strong spin-orbit interaction system, electrons experience an effective magnetic field due to the coupling between spin and orbital motion. In our experiment, we demonstrate the zero-bias peak splitting in the absence of magnetic field. Furthermore, tunable SOI strength enables us to realize gate-controlled evolution of zero-bias peak splitting.

[1] A. Kristensen et al., Phys. Rev. B 62 10950(2000)
[2] S.M. Cronenwett et al., Phys. Rev. Lett. 88 226805 (2002)

Keywords: Spin-orbit interaction, Kondo effect, Zero bias anomaly, InGaAs/InAs