The Kondo effect is theoretically studied in a quantum dot embedded in a mesoscopic ring. The ring is connected to two external leads, which enables the transport measurement. Using the "poor man's" scaling method, we obtain analytical expressions for the Kondo temperature TK as a function of the Aharonov-Bohm phase by the magnetic flux penetrating the ring. In this Kondo problem, there are two characteristic lengths. One is the screening length of the charge fluctuation, Lc=F/ |ε0|, where vF is the Fermi velocity and ε0 is the energy level in the quantum dot. The other is the screening length of the spin fluctuation, i.e., the size of the Kondo screening cloud, LK=F/TK. We obtain different expressions for TK for (i) LcLKL, (ii) L cLLK, and (iii) LLcLK, where L is the size of the ring. TK is markedly modulated by in cases (ii) and (iii), whereas it hardly depends on in case (i). We also derive logarithmic corrections to the conductance at temperature TTK and an analytical expression for the conductance at TTK, on the basis of the scaling analysis.
|ジャーナル||Physical Review B - Condensed Matter and Materials Physics|
|出版ステータス||Published - 2011 4 15|
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