Gary Wysin
Physics Research Topics

What I study:

Fine Particle Magnetism
Those magnetic disks have lots of tiny magnetic particles embedded in a matrix. We want to understand how the magnetic hysteresis of the particles (ability to store data) is affected by the particle size, surface anisotropy, and temperature, especially when the particles are made very small.

Nonlinear Topological Excitations
The spins in a magnetic material aren't always parallel, but can form very interesting configurations connecting different aligned regions (domain walls or solitons). They can also form textures where the spin arrows point so as to suggest a flow around some center, known as a vortex. These kinds of objects act like particles, are affected by applied magnetic field and temperature, and they can cause the magnet to disorder magnetically and demagnetize.

Time-Dependent Magnetic Fluctuations
The motions of domain walls and vortices cause time-dependent variations in the magnetism of the material. There are also linear spinwave excitations that do the same thing. We try to understand what these magnetic fluctuations can tell us about about these different types of magnetic excitations, and vice-versa.

Magnetic Models and Phase Transitions
The specific interaction of the spins usually has some anisotropy, for example, XY (easy-plane) and Ising (easy-axis) forms are common. Depending on the interaction, the magnetic excitations present can be responsible for phase transitions.

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Last update: October 2, 1996.
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