Hyper-chaotic magnetisation dynamics of two interacting dipoles

The present work is a numerical study of the deterministic spin dynamics of two interacting anisotropic magnetic particles in the presence of a time-dependent external magnetic field using the Landau–Lifshitz equation. Particles are coupled through the dipole–dipole interaction. The applied magnetic field is made of a constant longitudinal amplitude component and a time-dependent transversal amplitude component. Dynamical states obtained are represented by their Lyapunov exponents and bifurcation diagrams. The dependence on the largest and the second largest Lyapunov exponents, as a function of the magnitude and frequency of the applied magnetic field, and the relative distance between particles, is studied. The system presents multiple transitions between regular and chaotic behaviour depending on the control parameters. In particular, the system presents consistent hyper-chaotic states

Search for gamma ray bursts at Chacaltaya

A search for gamma-ray bursts in the GeV–TeV energy range has been performed by INCA, an air shower array working at 5200 m of altitude at the Chacaltaya Laboratory (Bolivia). The altitude of the detector and the use of the “single-particle technique” allows to lower the energy threshold up to few GeVs. No significant signals are observed during the occurrences of 125 GRBs detected by BATSE, and the obtained upper limits on the energy fluence in the interval 1–103 (1–102) GeV, range from 3.2 (8.6) ×10 −5 to 2.6 (7.0) ×10−2 erg cm −2 depending on the zenith angle of the events. These limits, thanks to the extreme altitude of INCA, are the lowest ever obtained in the sub-TeV energy region by a ground-based experiment

Localized chaotic patterns in weakly dissipative systems

A generalized parametrically driven damped nonlinear Schrödinger equation is used to describe, close to the resonance, the dynamics of weakly dissipative systems, like a harmonically coupled pendula chain or an easy-plane magnetic wire. The combined effects of parametric forcing, spatial coupling, and dissipation allows for the existence of stable non-trivial uniform states as well as homogeneous pattern states. The latter can be regular or chaotic. A new family of localized states that connect asymptotically a non-trivial uniform state with a spatio-temporal chaotic pattern is numerically found. We discuss the parameter range, where these localized structures exist. This article is dedicated to Prof. Helmut R. Brand on the occasion of his 60th birthday

Breather soliton solutions in a parametrically driven magnetic wire

In the present work we study the pattern formation in a magnetic wire forced by a transversal uniform and oscillatory magnetic field. This system is described in the continuous framework by the Landau-Lifshitz-Gilbert equation. We find numerically that the spatio-temporal magnetization field exhibits a family of breather soliton states. We characterize different types of breathers as a function of the amplitude and frequency of the driven field

Hyper-chaotic and chaotic synchronisation of two interacting dipoles

In the present work we study numerically the deterministic spin dynamics of two interacting anisotropic magnetic particles in the presence of a time dependent external magnetic field. The particles are coupled through their dipole-dipole interaction. The applied magnetic field is composed of a constant amplitude longitudinal component and other transversal with time dependent amplitude. The system is modelled by the dissipative Landau-Lifshitz equation. The different types of synchronisation have been studied finding that the system presents chaotic anti-synchronisation of the canonical component, for a wide range of parameters. Finally, we also found that the system exhibits phase hyper-chaotic synchronisation

Two-soliton precession state in a parametrically driven magnetic wire

56th Annual Conference on Magnetism and Magnetic Materials, Scottsdale, AZ, OCT 30-30, 201