ENERGY-LEVEL STATISTICS AND ORBITAL MAGNETISM OF INTERACTING ELECTRONS IN DISORDERED QUANTUM DOTS

The effects of the Coulomb interaction on energy-level statistics and orbital magnetism in disordered two-dimensional quantum dots are studi ed within a serf-consistent finite-temperature Hartree-Fock (HF) appro ximation, The nearest-neighbor level-spacing distribution of the HF en ergy at the Fermi level is shown to depend only weakly on magnetic fie lds. Fluctuations in the number of electrons, suppressed by a Coulomb gap produced at the Fermi energy, are also insensitive to magnetic fie lds. This insensitivity leads to the nonexistence of a large paramagne tism predicted for isolated mesoscopic systems of noninteracting diffu sive electrons.