From Localization to Delocalization in the Quantum Coulomb Glass

Abstract

We numerically investigate how electron–electron interactions influence the transport properties of disordered electrons in two dimensions. Our study is based on the quantum Coulomb glass model appropriately generalized to include the spin degrees of freedom. In order to obtain the low‐energy properties of this model we employ the Hartree‐Fock based diagonalization, an efficient numerical method similar to the configuration interaction approach in quantum chemistry. We calculate the dc conductance by means of the Kubo‐Greenwood formula and pay particular attention to the spin degrees of freedom. In agreement with earlier results we find that electron–electron interactions can cause delocalization. For spinful electrons this delocalization is significantly larger than for spinless electrons.

Parallel magnetoconductance of interacting electrons in a two-dimensional disordered system

“…Since in low density systems the ratio between the typical interaction energy and the Fermi energy, r s , is large (i.e., r s > 1), a natural explanation for the 2DMIT is that it is the result of the eei not taken into account in the original scaling theory. This has prompted an intensive theoretical effort including analytical 5 and numerical [6][7][8][9][10][11][12][13] work which tried to explain the 2DMIT as a result of delocalization by the eei. On the other hand, one may argue that the observed temperature dependence of the conductance is not a result of a metallic zero temperature phase but rather a manifestation of essentially "high" temperature physics.…”