Dynamics of ferromagnets: averaging methods, bifurcation diagrams, and thermal noise effects

Job Candidate Talk
Friday, January 31, 2014 - 1:00pm for 1 hour (actually 50 minutes)
Skiles 006
Katherine Newhall – Courant Institute
Michael Lacey
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 outline the problem of extending the analysis to spatially non-uniform magnets, leading to a transition state theory for infinite dimensional Hamiltonian systems.