g-factor and exchange energy in a few-electron lateral InGaAs quantum dot
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(a) SEM image of a quantum wire structure defined by etching trenches before deposition of the gate dielectric. The local finger gates are added schematically as yellow lines for device illustration. The scale bar is 200 nm. (b) Differential conductance as a function of source-drain bias and gate voltage , plotted on a logarithmic color scale, showing Coulomb blockade diamonds typical for the electron transport in a few-electron quantum dot. A parametric charge rearrangement can be seen at . (c) Addition energy as a function of the electron number in the dot, showing a typical shell filling behavior.
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(a) Conductance of the quantum dot measured in the linear response regime as a function of the magnetic field applied parallel to the quantum well layer. The numbers in parentheses and arrows indicate the level indices of the last filled single-particle levels and spin states of the levels. Here negative values of the g-factors are assumed. (b) Magnetic field evolution of the energy difference between the measured conductance peaks shown in (a). In each subplot, the orbital level and spin indices of the two associated states are indicated. (c) A simple model showing the four energy states of the dot studied in the region marked by the dashed box in Fig. 1(b). Here it is assumed that the two single-particle orbitals and are nearly degenerate and the negative exchange energy of the electrons favors a parallel spin filling.
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