Avalanches and self-organization in the dynamics of cellular magnetic domain patterns (invited)

Abstract

Cellular magnetic domain patterns in magnetic garnet films are an example of a spatially-extended metastable system whose evolution is limited by topological constraints. For sufficiently large applied magnetic fields, the entire pattern is under tension and can respond to local perturbations via large collective motions. In this regime disordered cellular patterns respond to small increases in applied field or to manual cell breakage via avalanches of sequential cell destruction which sweep through the pattern via the motion of cell walls. After one avalanche has stopped another can be started by a small increase in field or by another manual cell breakage; the system thus tends to self-organize into barely stable states. The measured distributions of avalanche size and duration are best fit by power laws. These features suggest that cellular avalanches may be an example of self-organized criticality.

Superconducting vortex avalanches, voltage bursts, and vortex plastic flow: Effect of the microscopic pinning landscape on the macroscopic properties

“…[9] considered avalanches in a continuous medium. [7] observed magnetic domains. [1] worked with Al2O3 particles and beach sand.…”

“…Method Power law exponent [9] Water droplets 1.9 [7] Magnetic garnet films 2.5 [1] Granular pile 2.5 [42] Granular pile 2.5 [2] Granular pile 2.2 [6] Rice grains 2.0 [5] Ramped granular slides 2.1 [11] Superconducting vortices 1.4 -2.2 [13] Superconducting vortices 1.7 -2.2 TABLE II. Exponents of power laws observed in various experiments.…”

“…Systems characterized by avalanche dynamics, in which energy dissipation occurs in sudden bursts of collective activity, are of particular interest. Avalanche behavior has been studied in many systems, including granular assemblies [1][2][3][4][5][6], magnetic domains [7], charge density waves [8], fluid flow down inclines [9,10], and flux lines in type-II superconductors [11][12][13].…”

Joint Services Electronics Program

“…In this geometry, with the detected radiation in the plane of incidence, the characteristic length scales vary typically from -100 A to 10 pm [6,7].…”

“…We have now carried out a study of the broadening of the R1 luminescence line of ruby, and of the photoluminescence peak in GaAs/Al0.3Gao. 7 As quantum wells, at 4.6 K to pressures of approximately 30 kbar. The methanol/ethanol mixture and also Xe, Ar and He were used as pressure transmitting media.…”