Materials Computation Center R'M' Martin and J'P' Leburton, University of Illinois, DMR 9976550 Spin

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Materials Computation Center, University of
Illinois Duane D. Johnson and Richard Martin, NSF
DMR-03-25939 Dynamics of Disordered
Nonequilibrium Systems Hysteresis, Noise, and
Domain Wall Dynamics in Systems Ranging from
Magnets to Earthquakes Karin Dahmen (UIUC,
MCC-UIUC)
Research Approach Earthquakes, magnets,
superconductors, and shape memory alloys
(Martensites) all respond to an external driving
force or field with crackling noise (avalanches).
We study universal (i.e.detail independent)
effects of disorder on the event size
distribution. Significant results We have found
surprisingly similar behavior for magnets and
earthquake faults. An extension of an existing
earthquake model to include aftershocks leads to
the same phase diagram for earthquakes as found
earlier for a model for Barkhausen Noise in
magnets (see figure to the right). This work
also supported by DMR 03-14279. With special
thanks to Mike Weissman and Jim Sethna.
Phase Diagram from Mehta, Dahmen, Ben-Zion,
2004, submitted for publication (epsilon is
related to the amount of geometrical
irregularities in the fault structure).