2008/05/01 by Yueheng Lan, Y. Charles Li, Y Charles Li
Physics and Astronomy · #Attractor #Bifurcation #Bifurcation diagram #Chaos control and synchronization #Chaotic #Limit (mathematics) #Limit cycle #Nanomagnet #Quantum chaos and dynamical systems #Spin (aerodynamics) #cond-mat.mtrl-sci #nlin.CD #nlin.PS #stochastic dynamics and bifurcation
paper · pdf · doi:10.1088/0951-7715/21/12/005
arxiv created 2008/05/01 · openalex publication_date 2008/11/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We study the spin dynamics of a long nanomagnet driven by an electrical current. In the case of only dc current, the spin dynamics has a sophisticated bifurcation diagram of attractors. One type of attractors is a weak chaos. On the other hand, in the case of only ac current, the spin dynamics has a rather simple bifurcation diagram of attractors. That is, for small Gilbert damping, when the ac current is below a critical value, the attractor is a limit cycle; above the critical value, the attractor is chaotic (turbulent). For normal Gilbert damping, the attractor is always a limit cycle in the physically interesting range of the ac current. We also developed a Melnikov integral theory for a theoretical prediction on the occurrence of chaos. Our Melnikov prediction seems to be performing quite well in the dc case. In the ac case, our Melnikov prediction seems to be predicting transient chaos. The sustained chaotic attractor seems to have extra support from parametric resonance leading to a turbulent state.