Anomalous Temperature Dependence of Coulomb Oscillations at Nearly Degenerate Levels

Peak heights of the Coulomb oscillation are examined based on the exact-diagonal calculations of many-body states in a quantum dot. where the Coulomb interaction energy is comparable with the one-electron level spacings. At nearly degenerate levels, high-spin states appear, in accordance with recent experimental results [Tarucha et at: Phys. Rev. Lett. 77 (1996) 3613], and some peaks of the conductance can increase with temperature. Two mechanisms are proposed for this anomalous temperature dependence. This phenomenon reflects a level spacing as small as one Kelvin and the total spin of the electronic states.