Creating Magnetic Rogue Waves and Nonlinear Effects
in Exchange Coupled Structures
Prof. Bob Camley
Department of Physics and Energy Science,
University of Colorado, Colorado Springs
Abstract: Rogue waves in oceans are a well-known phenomenon where a large wave that can overturn a ship spontaneously arises. We study whether it is possible to create a rogue wave in a magnetic system. We do this initially in micromagnetics by starting with a rogue wave configuration and letting it evolve in time. Instead of collecting data over the entire sample and using time reversal to reproduce the original wave, we collect time-dependent magnetic data at a small number of sites in the sample. Using time reversal on just 4 sites can create the rogue wave from a system in equilibrium. We also show that oscillating fields to create a rogue wave at one or more designated sites. Unlike the ocean, magnetic systems are anisotropic and tunable. We investigate how this influences the reconstruction of the rogue wave.
We also discuss nonlinear effects in ferromagnetically and antiferromagnetically exchange coupled structures. Here we find new, power-dependent, ferromagnetic resonance absorption peaks and hysteresis effects in a frequency scan that can span 10 GHz.
Biography: Bob Camley got his PhD in theoretical physics from the University of California, Irvine. He then spent 2.5 years at the Max Planck Institut in Stuttgart and shortly after that became a faculty member at the University of Colorado. His primary research has been in the thermal and electromagnetic properties of magnetic materials, linear and nonlinear excitations, and while visiting with Peter Grunberg he and Josef Barnas developed the first theoretical explanation of the Giant Magnetoresistance effect. He also has an interest in biophysics where he and colleagues at UCCS have been working on ways to make temperature visible in MRI images.