The Kondo effect in a S=0/S=1 quantum dot

Sasaki Satoshi, Naoki Asakawa, Shinichi Amaha, Wataru Izumida, Seigo Tarucha

Research output: Contribution to journalArticlepeer-review


We study the Kondo effect in a vertical quantum dot which is strongly coupled to leads. The electron number, N, and spin state, S, are clearly defined in this "artificial atom". We observe the Kondo effect in the low temperature transport characteristics when the dot has only one electron (N=l) and spin S=1/2. Furthermore, we observe a much stronger Kondo effect for N=2 when the spin singlet (S=0) - triplet (S=1) degeneracy is induced by magnetic field. We investigate the crossover of the Kondo effect when the two-electron ground state is changed from a spin-singlet via a singlet-triplet (S-T) degeneracy to a spin-triplet by sweeping the magnetic field. No Kondo effect is observed for the singlet ground state. The Kondo temperature is highest for the S-T degeneracy, and gradually decreases as the degeneracy is lifted such that the triplet is only the ground state. This behavior is consistent with the recent theory.

Original languageEnglish
Pages (from-to)73-76
Number of pages4
Journaljournal of the physical society of japan
Issue numberSUPPL. A
Publication statusPublished - 2003
Externally publishedYes


  • Degeneracy
  • Kondo effect
  • Quantum dot
  • Singlet-triplet
  • Spin
  • Zeeman

ASJC Scopus subject areas

  • Physics and Astronomy(all)


Dive into the research topics of 'The Kondo effect in a S=0/S=1 quantum dot'. Together they form a unique fingerprint.

Cite this