title: Dissipative structures induced by spin-transfer torques in nanopillars.
abstract: Macroscopic magnetic systems subjected to external forcing exhibit complex spatiotemporal behaviors as result of dissipative self-organization. Pattern formation from a uniform magnetization state, induced by the combination of a spin-polarized current and an external magnetic field, is studied for spin-transfer nano-oscillator devices. The system is described in the continuous limit by the Landau-Lifshitz-Gilbert equation. The bifurcation diagram of the quintessence parallel state, as a function of the external field and current, is elucidated. We have shown analytically that this state exhibits a spatial supercritical quintic bifurcation, which generates in two spatial dimensions a family of stationary stripes, squares, and superlattice states. Analytically, we have characterized their respective stabilities and bifurcations, which are controlled by a single dimensionless parameter. This scenario is confirmed numerically.
authors.affiliation: Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago, Chile.
authors.forename: Alejandro O
authors.initials: AO
authors.lastname: León
authors.affiliation: Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago, Chile.
authors.forename: Marcel G
authors.initials: MG
authors.lastname: Clerc
authors.affiliation: Laboratoire de Physique des Lasers, Atomes et Molécules, CNRS UMR 8523, Université des Sciences et Technologies de Lille - 59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Saliya
authors.initials: S
authors.lastname: Coulibaly