Synchronization induced by periodic inputs in finite NN-unit bistable Langevin models: The augmented moment method

We have studied the synchronization induced by periodic inputs applied to the finite $N$-unit coupled bistable Langevin model which is subjected to cross-correlated additive and multiplicative noises. Effects on the synchronization of the system size ($N$), the coupling strength and the cross-correlation between additive and multiplicative noises have been investigated with the use of the semi-analytical augmented moment method (AMM) which is the second-order moment approximation for local and global variables [H. Hasegawa, Phys. Rev. E {\bf 67} (2003) 041903]. A linear analysis of the stationary solution of AMM equations shows that the stability is improved (degraded) by positive (negative) couplings. Results of the nonlinear bistable Langevin model are compared to those of the linear Langevin model.Comment: 19 pages, 10 figures, the final version with a changed title, accepted in Physica

Zero-field and Larmor spinor precessions in a neutron polarimeter experiment

We present a neutron polarimetric experiment where two kinds of spinor precessions are observed: one is induced by different total energy of neutrons (zero-field precession) and the other is induced by a stationary guide field (Larmor precession). A characteristic of the former is the dependence of the energy-difference, which is in practice tuned by the frequency of the interacting oscillating magnetic field. In contrast the latter completely depends on the strength of the guide field, namely Larmor frequency. Our neutron-polarimetric experiment exhibits individual tuning as well as specific properties of each spinor precession, which assures the use of both spin precessions for multi-entangled spinor manipulation.Comment: 12 pages, 4 figure

Theory on the Temperature Dependence of Giant Magnetoresistance

The temperature dependence of the giant magnetoresistance (GMR) for currents parallel and perpendicular to the multilayer plane, is discussed by taking account of the random exchange potentials, phonon scatterings and spin fluctuations. The effect of spin fluctuations, which plays an important role at finite temperatures, is included by means of the static functional-integral method developed previously by the present author. Our model calculations well explain the observed features of the parallel and perpendicular GMR of Fe/Cr and Co/Cu multilayers recently reported by Gijs {\it et al}.Comment: 20 pages (LATEX), 5 figures available on request to [email protected]

Dynamics of Information Entropies in Nonextensive Systems

We have discussed dynamical properties of the Tsallis entropy and the generalized Fisher information in nonextensive systems described by the Langevin model subjected to additive and multiplicative noise. Analytical expressions for the time-dependent Tsallis entropy and generalized Fisher information have been obtained with the use of the $q$-moment approach to the Fokker-Planck equation developed in a previous study [H. Hasegawa, Phys. Rev. E {\bf 77}, 031133 (2008)]. Model calculations of the information entropies in response to an applied pulse and sinusoidal inputs have been presented.Comment: 21 pages, 8 figures, augmented text with changed titl