The recent discovery of superconductivity coexisting with weak itinerant ferromagnetism in the d-electron intermetallic compound ZrZn2 strongly suggests spin-fluctuation mediated superconductivity. Ab initio electronic structure calculations of the Fermi surface and generalized susceptibilities are performed to investigate the viability of longitudinal spin-fluctuation-induced spin-triplet supe...

We report a theoretical investigation on spin-Hall conductance fluctuation of disordered four-terminal devices in the presence of Rashba or/and Dresselhaus spin-orbital interactions in two dimensions. As a function of disorder, the spin-Hall conductance GsH shows ballistic, diffusive, and insulating transport regimes. For given spin-orbit interactions, a universal spin-Hall conductance fluctuat...

Using the equations recently presented by Kallosh et. al. (hep-th/9907124) and Giudice et. al. (hep-ph/9907510), we estimate the abundance of gravitinos created from the vacuum, in ‘new’ inflation models for which global supersymmetry is a good approximation. Gravitinos with helicity 1/2 are produced abundantly just after inflation, when their effective mass rises sharply, and even more abundan...

Extrapolation of perturbative nucleon spin fluctuation rates seems to suggest a strong suppression of weak interactions in supernova cores. We derive a new sum rule for the dynamical spin-density structure function which relates the spin fluctuation rate to the average nuclear interaction energy. For a bremsstrahlung like structure function profile we show that instead of strongly decreasing, t...

Observations of robust superconductivity in some of the iron based superconductors in the vicinity of a Lifshitz point where a spin density wave instability is suppressed as the hole band drops below the Fermi energy raise questions for spin-fluctuation theories. Here we discuss spin-fluctuation pairing for a bilayer Hubbard model, which goes through such a Lifshitz transition. We find s± pairi...

We have studied theoretically the electron spin relaxation in semiconductor quantum dots via interaction with nuclear spins. The relaxation is shown to be determined by three processes: (i) – the precession of the electron spin in the hyperfine field of the frozen fluctuation of the nuclear spins; (ii) – the precession of the nuclear spins in the hyperfine field of the electron; and (iii) – the...