Sergey V. Barabash

Structural and superconducting transitions in Mg 1 − x Al x B 2

From systematic ab initio calculations for the alloy system

Magnetoresistance of three-constituent composites: Percolation near a critical line

{\mathrm{Mg}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}{\mathrm{B}}_{2},

Conductivity due to classical phase fluctuations in a model for high-Tcsuperconductors

we find a strong tendency for the formation of a superstructure characterized by Al-rich layers. We also present a simple model, based on calculated energies and an estimate of the configurational entropy, which suggests that the alloy has two separate concentration regimes of phase separation, with critical points near

Negative magnetoresistance produced by Hall fluctuations in a ferromagnetic domain structure

x=0.25

Models for Enhanced Absorption in Inhomogeneous Superconductors

and

Transition Spectra for a BCS Superconductor with Multiple Gaps: Model Calculations for MgB2

x=0.75.

Superfluid inhomogeneity and microwave absorption in a model for thin high-Tc superconducting films

These results, together with calculations of electronic densities of states in several ionic arrangements, give a qualitative explanation for the observed structural instabilities, as well as the x dependence of the superconducting

Effective macroscopic response of a composite with small deviations from periodicity: application to colloidal crystals

{T}_{c}

Simple model for the variation of superfluid density with Zn concentration in YBa2Cu3O7−δ

for

Topics in the Physics of Inhomogeneous Materials

xl0.6.