Friday, May 3, 2013

1305.0242 (M. Amini et al.)

Multifractality and quantum-to-classical crossover in the Coulomb
anomaly at the Mott-Anderson metal-insulator transition

M. Amini, V. E. Kravtsov, M. Mueller
We study the interaction driven localization transition, which a recent experimentin Ga_{1-x}Mn_xAs has shown to come along with multifractal behavior of the local density of states (LDoS) and the intriguing persistence of critical correlations close to the Fermi level. We show that the bulk of these phenomena can be understood within a Hartree-Fock treatment of disordered, Coulomb-interacting spinless fermions. The scaling analysis of the LDoS correlation demonstrates multifractality with correlation dimension d_2=1.39. At the interaction-driven transition the states at the Fermi level become critical, whereas the bulk of the spectrum remains delocalized up to substantially stronger interactions. The mobility edge stays close to Fermi energy in a wide range of disorder strength, as the interaction strength is further increased. The localization transition is concomitant with the quantum-to-classical crossover in the shape of the pseudo-gap in the tunneling density of states, and with the proliferation of metastable HF solutions that suggest the onset of a glassy regime with poor screening properties.
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