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Theory Talk is an informal setting for fellow NC State physicists to see and hear work currently being pursued within the department. Speakers are encouraged to talk about work in progress and exchange ideas with the audience. Faculty, postdocs, and especially graduate students are encouraged to attend and present. Interested visitors and researchers from the Triangle area are also welcome.
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SPRING 2013 SCHEDULE
Mark Hoefer (NC State Mathematics)Magnetic Solitons, Theory and Realization
Fri., April 26, 3:30-4:30, Riddick 415 Conference Room
The concept of a soliton as a localized particle-like wave excitation that preserves its shape can be extended to systems that are far from thermodynamic equilibrium through the concept of a dissipative soliton, enabling the analysis of a broad range of physical, chemical, and biological nonlinear systems in which localized excitations are observed. The defining characteristic of a dissipative soliton is a delicate balance between nonlinearity and dispersion, as is the case for conservative solitons, with an additional balance between gain and loss. This talk will present a new manifestation of a dissipative soliton in the context of nanomagnetism. Experiment [1] and theory will be used to demonstrate the existence and properties of a localized oscillation mode called a magnetic droplet in a nanocontact based spin torque oscillator with perpendicular magnetic anisotropy. First predicted over 35 years ago [2], this is the first realization of a magnetic droplet soliton. Magnetic droplets are stable, controllable, strongly nonlinear, precessing dipoles exhibiting intriguing nonlinear physics.
[1] Spin Torque.Generated Magnetic Droplet Solitons, S. M. Mohseni, et al, Science, 339, 1295-1298 (2013).
[2] B. A. Ivanov, A. M. Kosevich, Zh. Eksp. Teor. Fiz. 72, 2000 (1977).