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

被引：0
作者：
Sasaki, Satoshi [1 ]
Asakawa, Naoki [2 ]
Amaha, Shinichi [2 ]
Izumida, Wataru
Tarucha, Seigo [1 ,2 ]
机构：
[1] NTT Corp, NTT Basic Res Labs, Tokyo, Japan
[2] Univ Tokyo, Dept Phys, Tokyo 1138654, Japan
来源：
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN | 2003年 / 72卷
关键词：
Kondo effect; quantum dot; spin; singlet-triplet; degeneracy; Zeeman;
D O I：
暂无
中图分类号：
O4 [物理学];
学科分类号：
0702 ;
摘要：
We study the Kondo effect in a vertical quantum dot whcih 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=1) 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.
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