Conductance of Mesoscopic Systems with Magnetic Impurities

We investigate the combined effects of magnetic impurities and applied magnetic field on the interference contribution to the conductance of disordered metals. We show that in a metal with weak spin-orbit interaction, the polarization of impurity spins reduces the rate of electron phase relaxation, thus enhancing the weak localization correction to conductivity. Magnetic field also suppresses thermal fluctuations of magnetic impurities, leading to a recovery of the conductance fluctuations. This recovery occurs regardless the strength of the spin-orbit interaction. We calculate the magnitudes of the weak localization correction and of the mesoscopic conductance fluctuations at an arbitrary level of the spin polarization induced by a magnetic field. Our analytical results for the ``$h/e$'' Aharonov-Bohm conductance oscillations in metal rings can be used to extract spin and gyromagnetic factor of magnetic impurities from existing experimental data.Comment: 18 pages, 8 figure

Pulsed chemical vapor deposition of Cu2S into a porous TiO 2 matrix

Chalcocite (Cu2S) has been deposited via pulsed chemical vapor deposition (PCVD) into a porous TiO2 matrix using hydrogen sulfide and a metal-organic precursor. The precursor used is similar to the more common Cu(hfac)(tmvs) precursor, but it is fluorin

THERMAL-CONDUCTIVITY OF C-60 AND C-70 CRYSTALS

We have performed thermal conductivity measurements on C60 and C70 crystals grown by sublimation. For single crystal C60, the thermal conductivity kappa is approximately 0.4 W/m K at room temperature and is nearly temperature independent down to 260 K. We observed a sharp orientiational phase transition at 260K, indicated by a 25% jump in kappa. Below 90 K, kappa is time dependent, which manifests itself as a shoulder-like structure at approximately 85 K. The temperature and time dependence of kappa below 260 K can be described by a simple model which accounts for the thermally activated hopping of C60 molecules between two nearly degenerate orientations, separated by an energy barrier of approximately 240 meV. It is found that solvents have a strong influence on the physical properties of C70 crystals. For solvent-free C70 crystal, kappa is about constant above 300 K. There is a broad first-order phase transition in kappa, at 300 K with a 25% jump. We associate this transition with the aligning of the fivefold axes of the C70 molecules along the c-axis of the hexagonal lattice. Upon further cooling, kappa, increases and is time independent