Spin and e-e interactions in quantum dots: Leading order corrections to universality and temperature effects

Article

关键词: BLOCKADE PEAK SPACINGS;    GROUND-STATE ENERGY;    MESOSCOPIC FLUCTUATIONS;    STATISTICAL-THEORY;    CONDUCTANCE;    OSCILLATIONS;    CHAOS;    MAGNETIZATION;    CAPACITANCE;    MOTION;   

DOI  :  10.1103/PhysRevB.66.155333

来源: SCIE

【 摘 要 】

We study the statistics of the spacing between Coulomb blockade conductance peaks in quantum dots with large dimensionless conductance g. Our starting point is the universal Hamiltonian-valid in the g-->infinity limit-which includes the charging energy, the single-electron energies (described by random matrix theory), and the average exchange interaction. We then calculate the magnitude of the most relevant finite g corrections, namely, the effect of surface charge, the gate effect, and the fluctuation of the residual e-e interaction. The resulting zero-temperature peak spacing distribution has corrections of order Delta/rootg. For typical values of the e-e interaction (r(s)similar to1) and simple geometries, theory predicts an asymmetric distribution with a significant even/odd effect. The width of the distribution is of order 0.3Delta, and its dominant feature is a large peak for the odd case, reminiscent of the delta function in the g-->infinity limit. We consider finite temperature effects next. Only after their inclusion is good agreement with the experimental results obtained. Even relatively low temperature causes large modifications in the peak spacing distribution: (i) its peak is dominated by the even distribution at k(B)Tsimilar to0.3Delta (at lower T a double peak appears), (ii) the even/odd effect is considerably weaker, (iii) the delta function is completely washed out, and (v) fluctuation of the coupling to the leads becomes relevant. Experiments aimed at observing the T=0 peak spacing distribution should therefore be done at k(B)T<0.1Delta for typical values of the e-e interaction.

【 授权许可】

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