arXiv subjects

D. Belitz

Publications and source records attributed to D. Belitz.

129 records · Page 8Linked to original sources

arXiv1994

Density Expansion for the Mobility of Electrons in Helium Gas

We calculate the electron mobility for a quantum Lorentz model, which provides a realistic description of electrons in Helium gas, to second order in the gas density. We show that this provides sufficient theoretical information to allow for an experimental observation of the famous logarithmic term in the density expansion. Detailed predictions, and a discussion of a suitable parameter range, for such an experiment are given.

cond-mat↗

arXiv1994

A Landau Theory for the Metal-Insulator Transition

The nonlinear $σ$-model for disordered interacting electrons is studied in spatial dimensions $d>4$. The critical behavior at the metal-insulator transition is determined exactly, and found to be that of a standard Landau-Ginzburg-Wilson $ϕ^4$-theory with the single-particle density of states as the order parameter. All static exponents have their mean-field values, and the dynamical exponent $z=3$. $\partial n/ \partial μ$ is critical with an exponent of $1/2$, and the electrical conductivity vanishes with an exponent $s=1$. The transition is qualitatively different from the one found in the same model in a $2+ε$ expansion.

cond-mat↗

arXiv1993

The Role of Cooperons in the Disordered Electron Problem: Logarithmic Corrections to Scaling Near the Metal-Insulator Transition

The effect of Cooperons on metal-insulator transitions (MIT) in disordered interacting electronic systems is studied. It is argued that previous results which concluded that Cooperons are qualitatively unimportant near the MIT might not be correct, and that the problem is much more complicated than had previously been realized. Although we do not completely solve the Cooperon problem, we propose a new approach that is at least internally consistent. Within this approach we find that in all universality classes where Cooperons are present, i.e. in the absence of magnetic impurities and magnetic fields, there are logarithmic corrections to scaling at the MIT. This result is used for a possible resolution of the so-called exponent puzzle for the conductivity near the MIT. A discussion of the relationship between theory and experiment is given. We also make a number of predictions concerning crossover effects which occur when a magnetic field is applied to a system with Cooperons.

cond-mat↗