Graduate Student / Postdoc Seminar

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Dynamics of Ferromagnets: Averaging Methods, Bifurcation Diagrams, and Thermal Noise Effects

Speaker: Katherine Newhall

Location: Warren Weaver Hall 1302

Date: Friday, March 28, 2014, 1 p.m.

Synopsis:

Driving nanomagnets by spin-polarized currents offers exciting prospects in magnetoelectronics, but the response of the magnet to such currents remains poorly understood. For a single domain ferromagnet, I will show that an averaged equation describing the diffusion of energy on a graph captures the low-damping dynamics of these systems. In particular, I compute the mean times of thermally assisted magnetization reversals in the finite temperature system, giving explicit expressions for the effective energy barriers conjectured to exist. I will then discuss the problem of extending the analysis to spatially non-uniform magnets, leading to a transition state theory for infinite dimensional Hamiltonian systems.