High resolution Hall measurements across the VO2 metal-insulator transition reveal impact of spatial phase separation.

Many strongly correlated transition metal oxides exhibit a metal-insulator transition (MIT), the manipulation of which is essential for their application as active device elements. However, such manipulation is hindered by lack of microscopic understanding of mechanisms involved in these transitions. A prototypical example is VO2, where previous studies indicated that the MIT resistance change correlate with changes in carrier density and mobility.

Magneto-optical spaser.

We present an electrodynamical model of a quantum plasmonic device--the magneto-optical (MO) spaser. It is shown that a spherical gain nanoparticle coated with a metallic MO shell can operate as a spaser amplifying circularly polarized surface plasmons. The MO spaser may be used in design of an optical isolator in plasmonic transmission lines as well as in spaser spectrometry of chiral molecules.

Resistance distribution in the hopping percolation model.

We study the distribution function P (rho) of the effective resistance rho in two- and three-dimensional random resistor networks of linear size L in the hopping percolation model. In this model each bond has a conductivity taken from an exponential form sigma proportional to exp (-kappar) , where kappa is a measure of disorder and r is a random number, 0< or = r < or =1 . We find that in both the usual strong-disorder regime L/ kappa(nu) >1 (not sensitive to removal of any single bond) and the extreme-disorder regime L/ kappa(nu) <1 (very sensitive to such a removal) the distribution depends only on L/kappa(nu) and can be well approximated by a log-normal function with dispersion b kappa(nu) /L , where b is a coefficient which depends on the type of lattice, and nu is the correlation critical exponent.

Percolation transition in a two-dimensional system of Ni granular ferromagnets.

We model magnetotransport features of the quenched condensed granular Ni thin films by a random two-dimensional resistor network in order to test the condition where a single bond dominates the system. The hopping conductivity is assumed to depend on the distance between neighboring ferromagnetic grains and the mutual orientation of the magnetic moments of these grains. We find that the quantity characterizing the transition from weak disorder (not sensitive to a change of a single bond resistivity) to strong disorder (very sensitive to such changes) scales as kappa/L(1/1.