Sphaleron transition rate in the classical 1+1 dimensional abelian Higgs model at finite temperature

We compute the sphaleron transition rate in the 1+1 dimensional abelian Higgs model at finite temperature, by real time simulation using the classical canonical ensemble.Comment: 3 pages to appear in the Proceedings of Lattice '93, Dallas, Texas, 12-16 October 1993, comes as a single postscript file (LaTeX source available from the authors), ITFA 93-3

Magnetic properties of a disordered Heisenberg binary spin system with long-range exchange

The influence of substitutional disorder on the magnetic properties of disordered Heisenberg binary spin systems with long-range exchange integrals is studied. The equation of motion for the magnon Green's function which is decoupled by the Tyablikov approximation is solved in the Blackman-Esterling-Berk(BEB) coherent potential approximation(CPA) framework, where the environmental disorder term is treated by virtual crystal approximation. The long-range exchange integrals include a power-law decaying and an oscillating Ruderman-Kittel-Kasuya-Yosida(RKKY) exchange interaction. The resulting spectral density, which is calculated by CPA self-consistent equation, is then used to estimate the magnetization and Curie temperature. The results show, in the case of the three-dimensional simple cubic systems, a strong influence of ferromagnetic long-range exchange integrals on the magnetization and Curie temperature of the systems, which is obviously different from the calculation of short-range interaction.Comment: 5 pages, 3 figures, to be accepted by PR

Energy levels of a parabolically confined quantum dot in the presence of spin-orbit interaction

We present a theoretical study of the energy levels in a parabolically confined quantum dot in the presence of the Rashba spin-orbit interaction (SOI). The features of some low-lying states in various strengths of the SOI are examined at finite magnetic fields. The presence of a magnetic field enhances the possibility of the spin polarization and the SOI leads to different energy dependence on magnetic fields applied. Furthermore, in high magnetic fields, the spectra of low-lying states show basic features of Fock-Darwin levels as well as Landau levels.Comment: 6 pages, 4 figures, accepted by J. Appl. Phy