California State University Long Beach

Monday, October 30, 2017
11:15 am in PH1-223

(Refreshments served at 10:45am in HSCl-224)

What is a skyrmion?
Dr. Héctor Ochoa
Department of Physics and Astronomy
University of California, Los Angeles

This question was a recurrent in-joke with my wife to make fun of people who uses ostentatious jargon when talking about Physics. Paradoxically (or not), I have become the object of my diffusion past jokes with the passage of time. As an act of contrition, I will try to answer this question in  simple terms, providing  also a historical background. In short: a skyrmion is an emergent particle associated with a whirling configuration of a vectorial order parameter. It was originally proposed by Tony Skyrme as a candidate for hadronic matter back in the early 60’s. However, skyrmions have been more profusely discussed in different contexts of Condensed Matter Physics. I will pay special attention to the case of magnetism, where skyrmions appear as textures of the spin-density field stabilized by relativistic interactions in some materials that receive the name of chiral magnets. I will describe the intriguing dynamics of these objects, which mimics the motion of charged particles in the presence of a strong magnetic field, and how this can be manipulated by non-equilibrium torques induced, for example, by electronic currents. In the last part of the talk, I will discuss quantum-size effects and connections with the quantum Hall effect.